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pH rising quickly

Discussion in 'Hydroponics / Aeroponics' started by eager, Jun 25, 2008.


    eager Active Member

    Hey guys,

    Second DWC grow, but first time with Advanced Nutrients. I've been having some issues keeping the pH at an optimal 5.6 and have had to keep adding pH down every few hours. Overnight, the pH will rise from 5.6 to 7.5+. My setup and nutrients are as follows:

    6 Gallon DWC with drip feeders
    250w HPS
    2'X2'X8' closet
    Res temp < 68
    Room temp < 85
    AN Sensi Grow A+B
    AN B-52

    I had a little spell with pythium and the hygrozyme has helped out quite a bit. During that time the pH dropped a lot. I'm in the 2nd week of veg now with the pythium under control.

    Is the pH rising a normal thing? I've read that it is, but I have also read that it should stabilize after a few days.

    firsttimegrowerr Well-Known Member

    Your res might be to small, the bigger the res the slower the ppm and ph will change. thats my guess but im a noob!

    eager Active Member

    Thanks for the Reply. I was wondering about that as well. I did a little research and started to think that it might not be too small. The tank itself is like 8 or 10 gallons and I've got 6 gallons of nutrient mix in it.

    Does anyone know if there is a maximum amount of pH down you can add to a 6 gal solution?

    firsttimegrowerr Well-Known Member

    You should be able to put watever amount you need without hurting the plants.
    Florida Girl

    Florida Girl Well-Known Member

    I agree...

    Also... how is the room temp 85 and the res temp 68 in that small space? Are you adding ice or frozen 2 liter bottles or do you have a res chiller? If you are adding frozen bottles.... are you doing it consistently? Fluctuating temps have an impact on PH drift.

    eager Active Member

    Thanks for the reply.

    I've insulated my tank and added an evaporative cooler (fan) to my tank. I've made it so that I can slide 2 huge frozen ice packs inbetween the insulation and the res. Temps are holding decently, but they did rise above 68 on my last grow and I think the pythium hung around and infected this grow.

    I was reading in another thread that the pH Up and Down might not be of good enough quality. I got them from the Stealth Hyrdroponics website so they could be shit. I wasn't happy with their stuff at all. I may need to run out to the hydro store again and grab some good ph adjusters.

    eager Active Member

    Just wanted to report back. I a newbie and didn't know what I was looking at dead roots :)

    I pulled each plant out of my dwc system and tugged on the roots a little. They broke free really easily so I started to clean them up some. After a while there were none hanging out of the net pots. I decided to pull the rockwool out of the hydroton. After I did that I noticed serious issues with deadness. So I cleaned each up and removed them from the rockwool. I tried to remove all the brown roots. I let each seedling roots soak in a hygrozyme solution in the sink while I sterilzed the system with a bleach solution. After doing that, I re-installed the seedlings directly in new hydroton with fresh nutes at 1/4 strength and a 45ml of hygrozyme (6 gal res). This morning the pH just rose a little bit, but nothing like what I was seeing. We'll see if i can keep the pythium away now. The plants look decent this morning.

    patjack Well-Known Member

    I don't recall did you say you were using a air pump for your rez, and are you using ro water? Also at some point to much ph down causes a problem (i can't remeber if it is to high mg or lockout of some sort, but after to much I have read that is bad) I haven't had the rising ph problem ever since switching to ro water

    eager Active Member


    I use RO water. I think the ph levels were caused by the amount of dead roots that were accumulating in my res. Just 4 days after a complete flush, the hygrozyme must have been working overtime, because I had a bunch of dead junk in the bottom of the res.

    It's been 18 hours since the change and I haven't noticed any difference in my plants. The pH hasn't risen above 6.4 yet, which is nice. I think this has made the difference, I just hope that I my plants are able to recover and have a decent yeild. I guess I'll just need to increase the veg time a couple weeks.

    hAEROin Active Member

    you will need some 35% hydrogen peroxide to CONTAIN any plythium. I don't think hygrozyme is much good for sterilizing. If your res temperature rises above 70 you will have trouble in most parts of the world.

    hugetom80s Well-Known Member

    As long as you keep your res temps low, your aeration (and thus dissolved oxygen) high, and the plants seem happy I wouldn't worry about whether or not you've completely eradicated the root rot. I've brought in perfectly good harvests with root systems that still had the remnants of a bout with pythium. It's a battle, and as long as the plants are winning it easily it's not too big a concern.

    Just sterilize extra good between grows to make sure it doesn't kill the next crop before it can get strong.

    Of course if you've still got the gremlin in your root system you need to keep an extra-close eye on it, and the effort your plants spend fighting it can slightly reduce your yield, but imo it's not worth losing sleep over if things are going well.

    surculus Well-Known Member

    I don't think hygrozyme is much good for sterilizing. what ? .................... hydrogen peroxide wont "fix" root rot!!!! hydroguard and hydrozyme are great and hydroguard adds a helpful bacteria subtillis bacillus which eats all rotten roots something hydrogen peroxide cant do and i have always had temps 70 degrees or more in my res

    hooked.on.ponics Well-Known Member

    I don't know what you're smoking, but it's an interesting kind of home-grown to be sure.

    Hydrogen peroxide absolutely does kill root rot. Root rot is caused by one of a few different kinds of fungus. High levels of oxygen kills fungus (and most everything else). Hydrogen peroxide is an unstable molecule that's just itching to get rid of the extra oxygen atom it carries so it can become ordinary, stable water. That's what the bubbles are - pure O2.

    However, an enzymatic agent like Sensizym is preferable to hydrogen peroxide since you don't have to worry about doing damage to your plants with high H2O2 doses.

    But the reason that people use peroxide to combat root rot is simple. It works.

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