# General questions on the "Lucas Formula"



## guff6387 (Nov 17, 2009)

I know the ratio is "0-8-16", is this for the General hydro "grow-bloom-micro"?

What range is the PPM/EC kept at? and is it kept at the same range for all stages of growth?

When I add back to the res with reverse osmosis water do I just add the 0-8-16 ratio until the ppm/ec is in my desired range and when should I dump the res?

What range is the Ph level kept at? By adding nutes you lower ph and adding RO water raises PH, right?

Has anyone used and had sucess with the nova series and was there much of any difference? what ratio do you use for the nova series?

How often should i check my res and add back to it?

I have an ebb and grow system, how often and when should I set the timer to flood the buckets at is it different for the different stages of growth (veg, flower)?
And i should not flood at night right?

Has anyone used any additives to the Lucas formula and noticed any difference?

Has anyone had success with using fox farm hydro? I use it in my soil and it always seems to burn my plants. 

Has anyone used advanced nutrients with the lucas formula? If yes, then how?

Any other suggestions for me?(this will be my first hydro grow, just bought an ebb and grow system off craig's list and i'm getting my medicinal card today )

Thank you very much for any info and when i get my card and buy a house I plan on making a thread and posting pics, i would appreciate any quality experenced advice and will be glad to award +rep


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## Resin225 (Nov 17, 2009)

guff6387 said:


> I know the ratio is "0-8-16", is this for the General hydro "grow-bloom-micro"?
> 
> Yes and no it is for GH but it is grow -MICRO-BLOOM.
> 
> ...


When you get your card, can I rent out a room from you? lol GL.


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## fatman7574 (Nov 17, 2009)

*General Hydroponics Flora Series Feeding Strategy - Lucas Formula* 

G-M-B (Grow-Micro-Bloom) 
0-5-10 - For Vegetative cycle (18/6) 
0-8-16 - For Flowering cycle (12/12) 

The numbers above indicate the number of milliliters (ml) of Flora Grow, Micro or Bloom formulas that used in one gallon (US Liquid) of nutrients. 

As you can see the ratio of Micro to Bloom is 1:2 ratio. No grow formula is used at all. The ratio always remains the same 1:2 but the actuall amounts diddere as t you add until to get the desires EC/ppm. The number of ml is just a general guide based upon starting a fresh reseroir of nutrients with RO water.

You will notice the Lucas Formula does not use the Flora &#8220;Grow&#8221; formula, you do not need to, the Flora "Micro" provides plenty of Nitrogen. 

_There are two ways to work with this formula:_ 

1. Top off the reservoir daily using a pH corrected water solution as required to maintain full reservoir level. After adding back an amount of water equal to the amount of your reservoir capacity you should change the reservoir and put in fresh solution. 

2. Top off the reservoir daily using a pH corrected 100% strength nutrient solution as required to maintain full reservoir level. Continue to use this nutrient solution without dumping the tank unless the PPM rises above acceptable levels. 

Between vegetative and flowering cycles you should dump your nutrients, then flush to remove salt buildups, then change to the other feeding program. Always shake your GH nutrient bottles before using them! 

For young plants, just transplanted into the hydro setup, give them 50% strength nutrient mix to prevent overfeeding them while their young. Gradually bring up the mix to full strength as they grow over the next few weeks or so. 

The lucas formula is normally intended for use with RO or near 0 PPM water. 

NOTE: The Lucas formula eliminates the need for Epsom salts to correct (Magnesium) Mg deficiencies in most normal feeding programs recommended by manufacturers. Cannabis needs a lot of Magnesium to thrive. 

The Flora Micro is providing the Nitrogen and the Magnesium in the proper balance, thus there is no need for the Grow formula and little or no room under the maximum acceptable ppm limit of 1600 @ 0.7 conversion. 

*Calculated EC/TDS levels:* 

EC microsiemen: 
0-4-8: 946 µS 
0-5-10: 1184 µS 
0-8-16: 1894 µS 

TDS @ 0.5 conversion: 
0-4-8 = 473 ppm 
0-5-10 = 592 ppm 
0-8-16 = 947 ppm 

TDS @ 0.7 conversion: 
0-4-8 = 663 ppm 
0-5-10 = 829 ppm 
0-8-16 = 1326 ppm 

*Addback Calculator - (For Advanced Users)* 

Say you were running the 0-8-16 formula, at 0.7 conversion with a 22 gallon res. When you first fill it up, your ppm will be around 1330. 

Now you have been growing for a week, and some of the water has been taken up by the plants, some has evaporated, and now your res is at 947 ppm. You need to get your ppm from 947 to 1330. Here is the equation: 

((target - current) / target) * 8 ml per gallon * res gallons = Flora Micro (ml) double this figure to get Flora Bloom (ml) 

Example: 

((1330 - 947) / 1330) * 8 * 22 
(383 / 1330) * 8 * 22 
0.3 * 8 * 22 = 53 ml Flora Micro 

53 ml Flora Micro, double that and you get 106 ml Flora Bloom. So 53 ml Flora Micro and 106 ml Flora Bloom to add back to your 22 gallon res to get you from 947 to 1330. 

pH is maintained at generally 5.5 to 5.8

Flora Nova I simply Lucas Formula with acid digetsed Humus and a little extra potash. The chief advanatage is it is a one part formula. As there are already chelates present the humus is likely more of a debit.

An two Parts Micro and bloom used at one part micro and tow parts bloom would work fine. There really is no need to use any supplements with the GH or AN tow part formulations.


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## Resin225 (Nov 17, 2009)

with all due respect fatman, I read in the ask lucas thread that the 0-5-10 is for cfl growing. Lucas said himself that 0-8-16 was for HID lights all the way through.


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## the church man (Nov 17, 2009)

this is from the "ask lucas" thread quoted from lucas himself

"yes, if you are vegging in 0-5-10, you can certainly just add more nutes and keep going, by raising the TDS. 

imvho, there is no need to dump the veg res

Im glad you asked about that, because Ive been meaning to talk a bit about vegetative nutes.
btw, before I blaze ahead, I dont recommend 0-5-10 as a veg formula actually, I only recommend it as a low light formula..

now lets talk about vegging

if newly rooted clones are transplanted into containers that are going to veg under fluoros, that is a sort of weak light situation, and using weak nutes makes sense, ~1000 ppm

but after the first week or two of fluoros, if the plants move to strong light, HPS light, or MH light, but with big lamps, you know, not fluoros, what is referred to as HID lighting.. then I want them to see full strength nutes.. 0-8-16.. ~13-1400ppm

now to the question of vegetative formulas
I find the use of FloraNovaGrow definitely kicks the vegging plants into greener, but also stretchier gear. In fact, vegging with FNGrow, the stalks turn into big hollow things that look like celery.. whereas when vegging with FNBloom, as I have always advocated in the past, vegging with bloom nutes, produces much more solid stems

sidenote, Clarke claims there is some belief that drug cultivars have hollow stems. I dont know if this is true, but I do know that higher doses of Nitrogen than the bloom recipe I know so well, produces hollow stems in plants that did not have them before..

anyway, back to the veg nute thang

I think vegging in FloraNovaGrow instead of FNBloom has some positive effects on kick starting the plants, so I devised an experiment..

a bubbler reservoir was mixed with FNGrow, and plants were vegged in it for a week, then, instead of dumping, when the light was flipped, all nute additions were FloraNovaBloom from then on.

so in this case the grow nutes stayed in the res, after veg ended, but only bloom nutes were added to the res when addbacks were made

this totally unreplicated experiment produced one of the highest yields that gardener has reported.. 1.75lbs per 1k... nothing outrageous, but, the cola size was huge!.. twice as fat as usually seen when veg is done with a low Nitrogen, bloom style nute

what Im driving at is the idea of feeding the stretch that Mr. Highway mentioned in the past.. the idea of nitrogen loading the initial days of 12/12.. I think he was on to something..

point of the story, even in this scenario, a res with Grow nutes during veg, not just weak bloom nutes, was not dumped, the Bloom nutes were simply added to the res as the bloom cycle went along consuming TDS..

so to your original, and insightful question, can one simply keep adding bloom nutes to a vegetative res, once the light is flipped, without dumping the veg res,,, my opinion is YES!

IrieItes
LucasI."




so... 0-5-10 is the formula to use if you have low intensity light i.e fluoros

and it is perfectly acceptable to NOT DUMP your res when switching over to bloom stage. just addback with bloom nutes. i suggest that if you are interested in the formula that you take your information straight from the source (google ask lucas and start reading) rather than ask others. in my experience, people are eager to give their interpretation of the formula. you should ask lucas instead


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## the church man (Nov 17, 2009)

sorry for all the cut and paste. there is no way that i could explain any of this better than it is already written. 

this is from http://www.angelfire.com/cantina/fourtwenty/

*by the way* you asked some really good questions. i hope that you find some really good answers





*Ebb/Flow Tips*

Unlike most active hydro systems where water enters containers from the top, ebb/flow generally employs subirrigation to flood the media from the bottom up. Because growing media is totally inundated it should be fast draining and provide plenty of aeration. To this end an inert hard coarse gravel with a particle diameter of approximately 1/2 inch is suitable. However, because of its weight, gravel is clumsy and laborious to clean between crops. Contemporary media includes manufactured alternatives with brand names such as Hydroton and Geolite, which are not only lightweight but offer better water retention due to their improved surface texture. Commonly referred to as _grow rocks_, these replacements take the guesswork out of selecting a suitable gravel and are the default media used in this article.
*Covers*



Covering the reservoir and growing bed serve several purposes.

Light is kept out of places where it would otherwise encourage the growth of algae
Plant debris is prevented from entering and rotting in growing media or in the reservoir
Evaporation is kept to a minimum (especially important when air is circulated by fans)
Humid conditions are maintained in the root zone
Use opaque inert material for covers. For growing beds, a white color facing the plants helps make better use of light. And though a black color is preferred to face the root side, as long as the material is opaque the purpose can be served with any color. Inert materials should be used wherever nutrient solution comes into contact with it, this is especially important for reservoir covers where condensation, or spray from air stone bubbles, constantly drips from the cover back into the reservoir volume. If the material is not inert, unwanted chemicals can leach from the material and contaminate the nutrient solution.
*Do I need to flood during the dark phase?*


No. Little or no water is taken up by plants during the dark phase. Set your last irrigation to begin shortly before the lights turn off, and the first to begin shortly after they turn on, then space the remainder of your irrigation cycles to occur equally between these two points.
*How deep should I flood?*


Ebb/flow systems generally flood through an overflow set approximately one to two inches below the top surface of the grow rock media. This prevents soggy conditions from persisting at the base of the plant's stem, and prevents salts from accumulating on exposed media due to evaporation (see Covers).
*For how long should I flood?*


The duration only needs to last until the overflow is reached, or if you have multiple growing beds until the overflow on the last bed is reached. Flooding for longer periods decreases the system's aeration potential.
*How often should I flood?*


Though a common question, it's not simple to answer at face value. The question implies that a given amount of water has been used over a given amount of time and now it needs to be replaced. Problem is, the given amount of water is relative to the volume of water held by _your_ media, and the given amount of time is relative to the rate at which _your_ plants are using that water, both of which require some effort from the grower to discover.
As far as irrigation frequency is concerned, an ideal situation exists when the quantity of media used in each pot, and the size of the plant grown in each pot, compliment one another. Or said another way, when the rate of water use and the available media water reserves are proportional, the same irrigation frequency aptly applies to every potted plant in the garden. If, for example, one potted plant twice the size would be grown with others half its size, a pot big enough to hold twice as much media as the others would be used in order to make twice as much water available to that plant between irrigations. By doing so, the same irrigation frequency would still apply to every potted plant in the garden because plant size and pot size were taken into consideration. Were no consideration given to plant or pot size, the irrigation frequency would need to be tuned to the _smallest pot with the largest plant_, relatively speaking, in order to avoid having that plant's water reserves compromised between irrigations.
Irrigation cycles are important because they must provide adequate water, nutrients and aeration to roots. Water and air cannot occupy the same space at the same time in the media, and because of that we use the timing of irrigations to strike an optimum balance between the media's air and water content over time. Too many irrigations compromise the optimum aeration ebb/flow is capable of delivering; too few and the water reserves held in the media between irrigations will not be sufficient to maintain an optimum supply of water and nutrients.
*The Hidden Reservoir*

Ebb/flow users pay close attention to their reservoir water volume (the holding tank), a volume that snaps into action when the water pump is switched on. But many fail to appreciate the hidden reservoir, _the water volume held in reserve by the media_, a volume that snaps into action after the holding tank pump is switched off and the excess water has drained from the media. If a grower doesn't know how much water the media in a pot can hold, and how fast the water is being used by the plant, he has no basis on which to benchmark his irrigation frequency. Using ebb/flow with grow rocks is often regarded as a method where overwatering is impossible, and it does indeed offer the user great latitude in the irrigation frequencies he uses. Although some growers are satisfied with their results after some trial and error or randomly guessing which frequencies to use, others growing under more challenging circumstances may want to know more about what's going on in their root zone before deciding. This implies finding the media water holding capacity, and the maximum water volume taken up by the plant, both of which can be attained rather easily.
*Finding your media's water holding capacity*

A simple test can tell you how much water your grow rocks hold. Measure two gallons of water and put it in a bucket. Measure one gallon of *bone dry* grow rocks and put them in a pot with drainage holes. Place the pot of grow rocks into the bucket of water, cover it, and let it sit overnight. Then remove the pot and allow the excess water to drain back into the bucket. Measure the water remaining in the bucket, the amount of water missing from the original two gallons is what one gallon of your grow rocks hold.
By applying this test data to the actual amount of media in your working pots you will know how much water is available to each plant between irrigations. For example, if one US gallon (3.8 liters) of your grow rock media holds 12 ounces (354ml) of water, but your working pots hold only 1/2 gallon of media, the potted plant would have 6 ounces (177ml) of nutrient solution available to it between irrigations.
*Assessing your maximum rate of water uptake*

This is done at a point in a crop's flowering cycle when the canopy is full and the plants are using the most water they'll ever use during the crop cycle, usually about 3/4 of the way through flowering. As water is used from the reservoir over time, the volume is periodically replenished by adding enough fresh water to bring the volume back to the_ full line_ marked on the reservoir. The volume of these add backs are recorded in a journal or log, from that data can be found how much water the system as a whole uses in one day. Because relative humidity, temperature and air flow affect water uptake, it's recommended to record this data for several consecutive days. Use the highest daily figure if your garden has no climate control or water uptake fluctuates markedly from day to day, you can use the average if conditions are reasonably constant.
By applying the daily maximum water uptake data collected during the 12 hour photoperiod to the number of potted plants, the rate of water uptake (per plant per hour of photoperiod) is discovered. When we know the hourly rate at which plants use water, and how much water they have in reserve, we can fine tune irrigation cycles to trigger at a time when a certain percentage of their water reserves have been used up. This insures that a plant's water and nutrient supply will be neither too plentiful nor inadequate, and in the process of doing that we have optimized aeration potential as well.


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## Bob Smith (Nov 17, 2009)

guff6387 said:


> I know the ratio is "0-8-16", is this for the General hydro "grow-bloom-micro"?
> 
> What range is the PPM/EC kept at? and is it kept at the same range for all stages of growth?
> 
> ...


From the top:

EC should be ~2.0 after nutes are added, assuming R/O water (PPM depends on what conversion you use).

It's kept the same for any plants in veg/flower stage, but freshly rooted clones, seedlings, and plants under fluoros should be at 0-5-10 to not burn them.

Always top your reservoir off with R/O water before adding nutes back - there's a formula for how much nutes to add, I forget it and am too lazy to Google - "ask Lucas" will take you to the formula.

You can dump the rez whenever you want - I'm shooting to go 2 months in-between changes, many dump more often then that, few even go longer then that - personal preference and plant health are the determining factors.

pH stays between 5.5 and 5.8 for me, and yes, you're correct about nutes lowering pH and water raising it.

I'm using Floranova Bloom right now and it's working fine - the difference is that you only need one bottle (the "bloom") as opposed to the micro and bloom that you need of Flora - also, the Nova is like fucking motor oil, the shit is thick.

That depends on the size of your reservoir - I have a 40 gallon reservoir for a 4x4 tray that I check every day, and add back R/O water when it gets down to 35 gallons, and nute if necessary.

Never used Ebb and Grow, can't comment, except that I use hydroton in my E&F and flood every two hours for ten minutes - plants love it, might even bump it up to every hour.

Never used additives and don't plan to - IMHO, they're 97% gimmicks and not worth the time, effort, and/or money.

Never used Fox Farms or Advanced, but there's a calculator/spreadsheet somewhere whereby you can convert any nutrient line to the Lucas Formula by using the proper amount of each "component" - do a search for it, pretty easy to find.

Good luck.


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## fatman7574 (Nov 17, 2009)

Guys like Bob Smith pointed out* EC *is what you need to be looking at not the ml of each added (unless you do ot have a TDS or EC meter). The ml amounts is just a guide line based u pon the assumption that nyone can mix up a ceratin EC using set ml amounts of each as listed without using a EC meter. This assumes pure water use though. Irregardless though the Lucas formula just means a 1 to 2 ratio of micro to Bloom. The sugge*sted *0-4-8: 0-5-10: 0-8-16: are all just different amounts of the standard 1 to 2 ratios of micro to bloom i.e twice as much blom as micro. ie the 0-8-16 is a suggestion to use twice as much as 0-4-8, it is not a different formula. The three ml amounts shown just produce the same Luca formula at different EC concentrations. The ratios (formula) remains the same. There is not a different formula for each phase of growth just differnt concentrations of the same formula.

Nutrient formulas are based uopn the ratio of the macro nutrients to each other. EC is a measurement of the concentration of the mixed formulation in solution.

That is why if you actually checked you would find that nearly all major nutrient manafacturers basically use the same formula, as 2-2-2 is the same formula as 4-4-4 or 8-8-8. Same formulas but different concentrations strengths. If the 2-2-2 was sold concenrated at x100 it would make a nutrient mix approximattely half the EC as a 4-4-4 x100 concentrate. They are still the same formulas though. Essentially this means the 2-2-2 should sell for half as much as the 4-4-4. However the manafacturers are not that ethical. If they can they will sell both at the same price.


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## fatman7574 (Nov 17, 2009)

the church man said:


> this is from the "ask lucas" thread quoted from lucas himself
> 
> "yes, if you are vegging in 0-5-10, you can certainly just add more nutes and keep going, by raising the TDS.
> 
> ...


*Hell, Lucas is just grower, no t an expert or demi god. He often cannot even remember what he has previously written. In actuallity 0-5-10 is a poor combination for low light grows. A mix of 5-5-0 would work better as in low light conditions ammonical ammonia is best taken up by plants. It would even be better to use hard water Micro instead of Micro with low lighting. GH grow has ammonical nitrogen (as does HW micro), Bloom does not, plus young vegative plants do not need the high levels of magnesium and phosphorus needed by budding plants.*

*The Lucas formula is not rocket science. It is just a way of not having to buy three different nutrient bottles. It is not the best growing method, just easy and convenient.*

*In reality it is not even a formula. It is simply a mix of existing formulas.*

*People seem to use the term formula wrong quite often when talking about how to mix GH formulas in differing amounts.*


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## tea tree (Nov 18, 2009)

http://www.generalhydroponics.com/ Look for the nutrient claculator. It is the shit. I get a kick out of it. I dont think Lucas would mind.


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## the church man (Nov 18, 2009)

does anyone know the actual nutritional value of the lucas method? like the real ppm value of each macro and micro nutrient? i've been looking around for it and information isn't adding up right


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## tea tree (Nov 18, 2009)

I did it. It adds up to flora nova grow and flora nova bloom, basically. I figured it all out, but that is what he says. There was a slight discrepancy with the bloom. But I used a lot of guesstimating. It was the ballpark and I was prob slightly off. The way to figure out the NPK is to look at the three part bottles. Then find what the max dose is. Like bloon is three tsp a gllon. That is the bottles NPK. It adds up.


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## Bob Smith (Nov 18, 2009)

tea tree said:


> I did it. It adds up to flora nova grow and flora nova bloom, basically. I figured it all out, but that is what he says. There was a slight discrepancy with the bloom. But I used a lot of guesstimating. It was the ballpark and I was prob slightly off. The way to figure out the NPK is to look at the three part bottles. Then find what the max dose is. Like bloon is three tsp a gllon. That is the bottles NPK. It adds up.


You should only be using the nova bloom - if you're using Flora, then use both micro and bloom, but if FloraNova, only bloom.

You don't use "grow" ever, in any of his "recipes".


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## fatman7574 (Nov 18, 2009)

Flora Nova Bloom is 1 part micro anf two parsts bloom with some humic acid addded. They just add the two parts concentrates together some acids and humus. The humus they add is called It is done in a heated pressure vessell. After all the preciptates that rae formed by mising the tow ingredianst aredissolved agin and the humus is dissolved they add a small dit od Potasium hydroxide to it tos stabilize the pH so that everything remains "almost" in solution. Any carbondioxide introdude eah time you open the bottle acuses some precipitates to form. What they use for humus is actually a soft coal. It is a brown soft low BTU coal. The humus is basically a form of orgainic chelates. With orgainic fertilizers they work in the way that chemical chelates work in order to make metals avialable, especially iron. The use of humus in chemical fertilzers is probably more of a debit than an asset, but it sells anyway.metals esopecially iron ork in chemical fertilizers.

This is based upon an analysis of bottled GH micro and bloom combined on a 1 to 2 , so: N=5, P=10, K=9 and M=3 
i.e the Lucas Formula

N=176, P=133, K=300, M=100, Calcium=166


Part A.
Calcium Nitrate 75.3 
Iron Chelate 2.25

Part B.
Mono Potassium Phosphate 104.8
Magnesium Sulfate 67.4

Trace Part B.
Manganese Sulfate 0.448
Boric Acid 0.085
Zinc Sulfate 0.009
Copper Sulfate 0.003
Ammonium Molybdate 0.0014 


This recipe is for a x100 concentrate. That means a combination of 2.5 gallons of Part A. And 2.5 gallons of Part B to which the trace nutrients are added. With all mixed to gether in a dry mix you have the dry mix equivalent of Floro Nova Bloom without the added humus.

This should cost about $35 to mix up. ie about $7 per gallon.


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## sherriberry (Nov 25, 2009)

anything bad happen if you use 2 nute brands simultaneously?

ive been using bcuzz 2 part grow, and started doing this lucas stuff using AN micro and bloom, just topping off containers, and keeping the ppm where it should be.

Also, what happens if you use water softened water, in a sprayer setup where roots are fully exposed like stinkbuds setup? (water has a base ppm of 300)


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## fatman7574 (Nov 25, 2009)

A water softener (resin beads charged with salt brine) excaj hanges calcium ions with sodium ions. Sosium is only need in a very small tarce amount. So small an amount is is not added to hydroponic nutrient formulations, Water that has been run through aw aet softener should be run through a RO filter.

Mis xing brands does not ammter as long as you know wja hat you mixing so t you will j know the ending analsis. Most chemical nutrient formulation are two part or three part formulations and really the top brands don't differ all that much if you are just buying say micro bloom and a veg formula. Some are jsut more concentrated is the major difference. Once you get away from the basic formulations the differences can be quite pronounced.


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## Saveahoe (May 16, 2021)

Resin225 said:


> with all due respect fatman, I read in the ask lucas thread that the 0-5-10 is for cfl growing. Lucas said himself that 0-8-16 was for HID lights all the way through.


I have a question due we feed straight nutrients only or water in between


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## Qube (May 16, 2021)

I think you'll need to be traveling 88 mph to get an answer.


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