Desperate For Advice On Ph Issues In Small 2 Gallon Reservoir

This is my first grow and I'm having trouble. Everything else is dialed in, so I think it must be related to the daily 5.6-6.1 pH swing I see and/or the pH down that I'm constantly having to add every single day.

My plant often looks droopy as if it's not getting enough oxygen (which it is), various leaf tips curl either up or down, and most of the lower fan leaves have some degree of brown "rust" spots which point to some type of deficiency.

I'm running out of ideas and my only guess at this point is that one or more nutes are getting locked out once the pH down/phosphorus in the res gets too high??

I'm going to change the res in just a bit and see if she looks any better in the morning, but I'm desperate for any input at this point if you have a minute to chime in. Here's what I'm looking at...

Set up: Supercloset superbox w/ about 2 gallons in the reservoir
Plants: 1 single feminized auto, CBD Crack (28 days old and pre-flowering)
Light: 200w CFL on top and (2) 100w CFLs side lights. 20 hours on, 4 hours off.
Nutes: ~600ppm Technaflora (recipe for success)
Water: I start with distilled, add nutes, then pH to 5.6
Water temp: 64-72F (averages about 68F)
Air temp: 64-80F (averages about 76-78F with the lights on)
Humidity: 45-60% (averages about 50%)
Roots: Healthy and white. Starting to fill the res. 1/2 inch "hairs" everywhere.
pH: 5.6-6.1 swing every day, requiring pH down every day

I've done a ridiculous amount of research on everything, but as you know there aren't many "one size fits all" answers, and everyone has differing opinions. But here are some of the things I'm thinking about, if you know about or can comment on any of them ...

1. Can you have a healthy hydro plant if your pH swings from 5.6-6.1 and then back to 5.6 every day?

2. Is it even realistic to try to grow in a 2 gallon res? Do I need to use something at least 5-10 gallons in order to reduce the pH problems, and just waste a bunch of money on extra nutes?

This set up has 8 net pots and while you could never grow 8 plants in this box I've watched a bunch of YouTube videos where guys have grown multiple plants in the 2 gal res so hmmm

3. Is there something else I could be using besides GH pH down? I've read that another brand called Advanced Nutrients has a pH down that supposedly "lasts" a lot longer, requiring less to be added. Or should I be using vinegar or something else that won't cause a nute lockout and be better for my plant?

4. Am I making a huge noob mistake and totally missing something here??

Sorry for the long post. If you made it this far you're awesome!

You may not have a pH problem, per se. When did you last calibrate your pH pen?

Mine was reading 7.0 when it was actually 8.0. Big Difference that caused a lot of plant health issues

pH pen should be calibrated at least once a month

dsiomtw said:

w/ about 2 gallons in the reservoir

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there's your problem. 2 gals will be almost impossble to maintain stable pH

Try mixing 50% tap in with your distilled to bring the KH up.

PetFlora said:

You may not have a pH problem, per se. When did you last calibrate your pH pen?

Mine was reading 7.0 when it was actually 8.0. Big Difference that caused a lot of plant health issues

pH pen should be calibrated at least once a month

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Well this my first grow and everything is brand new. I'm using the Bluelabs meter to monitor PPM, water temp and pH and the pH probe was calibrated about a month ago when I first got it.

rkymtnman said:

there's your problem. 2 gals will be almost impossble to maintain stable pH

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The weird part is that I can find about a dozen videos on YouTube where people are growing several plants in this same set up, with only 2 gallons, and their plants look amazing. If my problem isn't the constant pH down that I'm adding every day I'm totally at a loss, because everything is dialed in 100%. This sucks because I want to start a new grow but at this point I have absolutely no idea what to do differently.

XipXipXoom said:

Try mixing 50% tap in with your distilled to bring the KH up.

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Our "tap" water is softened, and I'm not sure how that affects things, but I will certainly look into it and give it a try. Thanks!

dsiomtw said:

The weird part is that I can find about a dozen videos on YouTube where people are growing several plants in this same set up, with only 2 gallons, and their plants look amazing. If my problem isn't the constant pH down that I'm adding every day I'm totally at a loss, because everything is dialed in 100%. This sucks because I want to start a new grow but at this point I have absolutely no idea what to do differently.

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going from 5.5 to 6.1 daily isn't horrible. you should only be adjusting at a max twice daily FYI. once the root ball gets larger, your 2 gal is going to be more like 1 gal which will probably make it swing even more.

dsiomtw said:

Our "tap" water is softened

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if you mean you add salt, i wouldn't use it. will be too much sodium. even more problems.

Ya I only adjust the pH once a day. If this is not my problem then I'll start focusing elsewhere. I just can't think of anything because everything else is completely dialed in, and I thought for sure the high amounts of phosphorus I'm adding must be locking out other nutes. Who knows maybe I'm just lucky and grew a bad seed. I guess that's the downside of growing a single plant, especially the first time. I have no idea what's "normal" or not.

As far as the water goes, I also have an RO unit I could use to filter the softened water, but at the end of the day I don't mind adding pH down every day. If this is normal and not causing my problem I'll start looking elsewhere, just not sure where.

dsiomtw said:

Ya I only adjust the pH once a day. If this is not my problem then I'll start focusing elsewhere. I just can't think of anything because everything else is completely dialed in, and I thought for sure the high amounts of phosphorus I'm adding must be locking out other nutes. Who knows maybe I'm just lucky and grew a bad seed. I guess that's the downside of growing a single plant, especially the first time. I have no idea what's "normal" or not.

As far as the water goes, I also have an RO unit I could use to filter the softened water, but at the end of the day I don't mind adding pH down every day. If this is normal and not causing my problem I'll start looking elsewhere, just not sure where.

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if your pH is going up and your EC/ppm is going down daily, that's good.

just the nature of the beast: the less the amount of water, the less it will help buffer your pH.

as long as you don't have any root rot, continue on.

with such a small res, you could even try just draining and refilling it once a day or once every 2 days. then you don't have to worry about pH down build up.

rkymtnman said:

going from 5.5 to 6.1 daily isn't horrible. you should only be adjusting at a max twice daily FYI. once the root ball gets larger, your 2 gal is going to be more like 1 gal which will probably make it swing even more.

if you mean you add salt, i wouldn't use it. will be too much sodium. even more problems.

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Bigger the res the easier it is to manage. If you can use a 5 gal bucket per plant with an air stone your set

Don't use softened water

Thanks guys. I will certainly carry on, but my plant has some real issues so I need to figure out what's causing it. I will definitely try changing the res every day for a week and see if she looks any better a week from now. I guess that will tell me if the pH/phosphorus is part of the problem one way or another.

If not I feel like I'm screwed though, because everything else is dialed in and I have no idea what to do next...

dsiomtw said:

but my plant has some real issues

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how about some pics?

one thing i noticed is that your ppm seems pretty high especially for an auto.

The ppm is in the recommended range of 500-800ppm for veg, provided by both Technaflora and Supercloset, so I'm just following what they said. You think 600ppm is high? For autos it seems like most people recommend working up to about half strength. Isn't 600ppm around "half" ?

Here are some pics. The first pic shows the general "droopiness" of the plant in general and some tips curling both up and down, the second pic shows a bottom fan leaf with the brown spots (I've already had to defoliate several lower fan leaves that were 50-100% destroyed), the third pic shows the new growth up top which actually looks decent overall, the 4th pic shows the roots which have only started turning slight brown as I have increased PPM (they aren't slimy at all), and the last pic shows the top of the plant and lights which are 6-8" away. Anything jump out at you?

they don't look bad at all. i'd drop your temps a bit. maybe 72F instead of the 78.8F in bottom pic

dsiomtw said:

The ppm is in the recommended range of 500-800ppm for veg, provided by both Technaflora and Supercloset, so I'm just following what they said. You think 600ppm is high? For autos it seems like most people recommend working up to about half strength. Isn't 600ppm around "half" ?

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ppm/EC is all relative to what your plant can handle. as an example, i grow at high altitude and anything much above 1.2 EC (600 ppm ish) will burn my tips. it's easier to work up to more nutes then to fix an over-nute situation

Drop the air temps to 72F? Hmm I can certainly try. Everything I've read said that 75-80F when lights are on should be totally acceptable, no? Does it look like my plant is heat stressed to you?

dsiomtw said:

Does it look like my plant is heat stressed to you?

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it won't hurt. unless you have a infrared themometer to measure leaf temps?

your gauge is on the side, not where the plant itself iis att. it's probably closer to 80 to 82 at the plant

and if that leaf curling doesn't get better looking after lower temps , maybe add some distilled water to get your ppm down just a bit.

you aren't far off. the devil is in the details.

Actually I do! I've already opened the window to cool down the room some more, and while the gauge reads 75.8F at the back of the box, the leaf temp near the top is 74.8F according to my temp gun. So it seems to be pretty close.



I guess that means the leaf temps were previously getting as high as 78-80, which although high should be OK based on what I've read. But I will certainly try dropping the temps.

If I drop the ambient room air temps 8 degrees, my res water temp is also going to drop roughly 8 degrees, putting it right around 60 which is borderline too cold. Will I need to then add a heater to my res?? Maybe I'll try dropping things 5 degrees and see if that helps at all...

rkymtnman said:

going from 5.5 to 6.1 daily isn't horrible. you should only be adjusting at a max twice daily FYI. once the root ball gets larger, your 2 gal is going to be more like 1 gal which will probably make it swing even more.

if you mean you add salt, i wouldn't use it. will be too much sodium. even more problems.

Click to expand...

If you have to adjust your PH twice daily you are seriously doing something wrong. That's WAYYYYYY more work than necessary, i think you might want to reevaluate your hydro setup. I PH mine 1 time per week and top off in mean time and my plants are healthy and vigorous.

Also 2 gallon rez is a pefect size, it's the standard size for the rez on the waterfarm(what i use), which is one of the most used hydro systems ever created.

dsiomtw said:

If I drop the ambient room air temps 8 degrees, my res water temp is also going to drop roughly 8 degrees, putting it right around 60 which is borderline too cold.

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agreed. set your room at whatever will keep your water temps at 65F.
the clawing is N toxicity so drop your ppm a bit. the rust is mag defic so you might want to add some epsom salts.

Yodaweed said:

Also 2 gallon rez is a pefect size,

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a supercloset is a 6 site dwc with a 2 gal reservoir. re-read first post by the OP.