Rising pH

Zandor (or anyone else knowledgable about such matters),

This novice can't seem to keep his nutrient solution at a constant pH. I'll set the pH to about 5.3, but within 7 or 8 hours, it will rise to over 7 (around 7.1 or so). I correct the pH by adding granulated citric acid, which takes it back down to the low 5's, but again, in only a few hours, it's risen well above the applicable range (5.2-5.9). I know pH usually drifts up (and this is even beneficial to the plant as it can absorb a wider range of nutrients as the pH changes), but I was always under the impression that normal upward pH drift is much slower - on the order of several days or more, not several hours as I have been experiencing.

My reservoir is small - only about 7 liters, and I have an airstone to keep things aerated and bubbling, and I change the entire solution every week. I also use only organic nutes (Advanced Nutrients Iguana Juice, Enggy's Humic/Fulvic Acid, etc.). I've already lost my very first plant (sob), but I have a garden of new seedlings that are just beginning to open up. Any thoughts or help you can give would be MOST appreciated.

Yo Im a recent graduated hort major, and my best advice would be to keep your pH around 5.8 to 6.2. Your plants can't take up most of there micro nutrients at a pH level below 5.4 or so. A lower pH is only better toward your finishing stages. The reason your pH keeps rising is b/c you are using good stable nutrients and they are designed to stay around 6.0, if you really want to drop your pH that low i would cut out the fulvic acid and that should help.



green leaves

COOL! :)

A hort major who graduated :) :) :)

Hope you stick around....perhaps you can give us some more fundamentals on plant reactions and interactions :)

There is a chart in the FAQ section that shows the nutrient uptake at different Ph levels. DL it to your desktop for reference, Ph is different for dirt and hydro so match the Ph requirements to the method of growing you are using.

Zandor,

Thanks for the reply. Unfortunately, I wasn't asking about what pH I should use, or which nutrients uptake at what pH. I asked a very specific question about why my pH rises as much as 0.2 per hour, and what I might be able to do about it.

Your answer, to read the FAQ section regarding proper pH levels, had absolutely nothing to do with my question, which, again, was why does my pH rise so fast and how can I slow it down.


I've seen many questions posted on this forum where your response was to read the FAQ section, and appropriately so, because the particular question asked has already been answered there. Moreover, in many of those responses, you've indicated your frustration that the person who posted the question didn't read the forum user guide carefully enough so that he/she would know to check in the FAQ section first to see if their question is answered before posting. So I'm certain you can understand my frustration that you didn't read my question carefully enough to provide a meaningful response. Could you please do that now. Me and my plants would be extremely grateful.

By the way, thanks to Str8jeepin4pack for the advice. I've raised the base pH level to around 5.8 (not 5.2 like I had been doing).

Green Dreams to all.

Really it is you just may not have understood is all, I will try to explain.

Different nutrients are available to the plant at different Ph levels the chart shows that. In turn the plant expels un-used nutrients as well back into the res. That is why the TDS is only accurate when you first mix it. Same theory applies to Ph. The plant expels byproducts that affect the TDS and Ph as well. Depending on the cycle you are in and what nutrients you are using to maintain balance.
Lemon juice for example works fast but it does not hold long the plant drinks up what it wants and expels back the un-used parts it does not need in that cycle. That is what affects your Ph and makes it rise or drop.

The only thing you can do is to keep it in check. Some Ph up last longer then others. I adjust mine twice a day minimum some day's three times. Like when they first enter the flower cycle the Ph move around more then the last 3 weeks of harvest.

So you see the chart and knowing the cycle you can predict how much the Ph will move around on you.

If you want to slow down how much the Ph changes try different Ph up or down products not all of them are the same.

Zandor,

Thank you very much for the response. As far as troubleshooting goes, and by way of background info:

I use only distilled water, so theoretically I'm starting out at 0 ppm;

I germinate using the paper towel method (which is highly effective for me - 20 out of 25 seeds sprouted in my latest attempt, 18 of which are now nice seedlings);

I don't use rockwool (I use foam cubes for the seedlings); and

I use granulated citric acid for pH down (I use potassium bi-carbonate whenever I do use pH up).

Also, I don't have a TDS/EC meter, so I don't really know how concentrated my nute solution is at any given moment. I mix the nutes stricly according to the manufacturer's recommendation (in my case, that would be Advanced Nutrients. They provide an online nutrient calculator which can be found at: http://www.advancednutrients.com/nutcalc3public/).

Additionally, I just purchased an external canister-style filter (for aquariums) in the hopes that it will help keep the pH at a more constant level. I've read that these filters promote the growth of beneficial bacteria which denitrify the nute solution by removing nitrite and nitrate wastes. After I install the filter, and as soon as I can determine how effective it is, I will post the results.

Thanks again for your time and attention, Zandor. I sincerely appreciate it.

Green Dreams,
Anchman