Question about RDWC addback

5BY5LEC

Well-Known Member
Hey all. I am running an 4 site RDWC holding about 19 gallons of water. First grow, just built the system.

Here lately my water has been going down and so have my PPMs. I have a chiller and using bennies so I am trying to go two weeks between changes.
My addback method:

I started at 400ppm. Today I am at 340. This means the plants ate 60ppm's or 15% from where I started.
I originally added 33ml each of GH Trio to the 18 gallons.
15% of my original 33ml is 4.9ml or so.

Add 4.9ml of each to whatever amount of water the plants have used and dump it back it. Repeat every few days.

Is this a viable method to use for my grow or am I understanding something wrong? Alot of people say to add water but I hate watching my PPM's drop when I add water. About to try this tonight for the first time. Thanks!
 

NGA

Well-Known Member
I never top up with water unless I need to raise ph,my nutes are always pre made and top up as needed , that said I flush every week or less ,that's the way I've always done it
 

Airwalker16

Well-Known Member
If you're adding back to your system, always do so with full strength(as to what you're using as normal) nutrient enriched water.
 

5BY5LEC

Well-Known Member
Thanks! When you pre-make nutes are you just making up what you originally filled the system with?
 
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Reactions: NGA

NGA

Well-Known Member
i use mega crop, 1 part powder ,1 gram per litre, I mix a few 20 litre jugs have them sitting there use as I need ,that is normal feed
 

5BY5LEC

Well-Known Member
If you're adding back to your system, always do so with full strength(as to what you're using as normal) nutrient enriched water.
Ok. Are there times you should vary how strong the mix is, according to how much ppms the plant has eaten?
 

NGA

Well-Known Member
than you just add water,or maybe flush your plants , when you see this it's time to act,I'm old school I just look at my plants I can tell if their not happy, keep an eye on your roots,keep temp down don't make rash ,decisions ,if you don't know just ask someone will help you
 

5BY5LEC

Well-Known Member
Cool thanks. I am not quite to half a teaspoon yet. I am about 2ml/gal at the moment and 1ml/gal on the calmag. That brings my PPMs to around 350-400.
I tried my 15% thing and it brought my PPM's from 340 right up to 390-400. I added the gallon slowly over the course of 5-10min as not to shock the plants.

Question about week 3-4
Do I work my way up to 1tsp/gal during transition? Thats 5ml/gal and more than double what I am adding now.
 

Airwalker16

Well-Known Member
Cool thanks. I am not quite to half a teaspoon yet. I am about 2ml/gal at the moment and 1ml/gal on the calmag. That brings my PPMs to around 350-400.
I tried my 15% thing and it brought my PPM's from 340 right up to 390-400. I added the gallon slowly over the course of 5-10min as not to shock the plants.

Question about week 3-4
Do I work my way up to 1tsp/gal during transition? Thats 5ml/gal and more than double what I am adding now.
Are you using reverse osmosis water.
 

5BY5LEC

Well-Known Member
I am going to try this out sometime but I honestly think with a dwc/rdwc you can let your PPM's drop pretty low before you see anything bad.
Not certain on this, but I am getting the idea that letting your PPM's drop will not really hurt anything, but one can maximize growth but keeping them up through addbacks with nutes.
I added back water last night, I mixed up a gallon of almost 1000ppm water (my 15% that I lost from the total of 19) and dumped it in. It was still about a gallon low so I mixed up another gallon of my regular nutes and dumped it in.
Ended up back at my original 400 last night when I checked it. This morning it is flipping between 390-400 and my PH is still at 5.8.

If they start to look shitty or I see brown tips I will post it right away. If they keep using PPM's they are not overfed.
 

5BY5LEC

Well-Known Member
I have a ecoplus 1/4 horse. It is big for my setup but for the price the guy offered me, I couldnt refuse. It runs for about 10 min a couple times a day.
The roots have been looking sweet lately. I need to get some pics.

If I were forced to buy a new one I would get a AA 1/10 horse.
 
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