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Any thoughts on pH problem?

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Old 03-12-2010, 10:26 PM
GpsFrontier GpsFrontier is offline
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Join Date: Mar 2009
Location: Lake Havasu AZ.
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Default Any thoughts on pH problem?

I have a problem stabilizing pH levels for my pea plants that I just can't figure out.

I am using General Hydroponics Flora Series nutrients. I don't have a PPM or TDS meter, but I mix the nutrients at 10mL per gallon of each. I use RO water, I mix it with about 10% hard water from the outside tap (I boil first to get rid of ant pathogens). When I mix fresh nutrients I mix everything first before checking and adjusting pH. When replacing water, I either check pH of the fresh water before adding it, or check and adjust the whole reservoir after adding it.

The pH of the RO will vary for some reason, sometimes it's low, sometimes it's high, and sometimes it's just fine, so I need to check pH every time I add water. That's why the problem has gone on so long, I just thought I wasn't checking the water I was replacing it with it closely enough. But now I am making sure I check it. I try to keep the pH at 6.0, but in less than 24 hours it went from 6.0 to about 7.5 or 8.0 before adding any water. The two pH test samples were taken in the last two days. The one closest to the bottle of drops was taken yesterday and in less than 24 hours without adding any replacement water from the time I had it at 6.0. The other one I just took now, I added 2 or 3 gallons of replacement water last night but no pH adjuster (it dosen't seem to help anyway , and I'm almost out).

I use earth juice dry pH adjusters, they are dry adjusters so I don't think they would go stale, and I don't leave the lid off so I am sure they have never been contaminated with anything. Also I have 3 other systems going and don't notice any pH problems with them. I went with the earth juice mostly because of shipping cost, the liquids weigh more and simply cost more to ship. Each one of these dry adjusters were one pound but seems to go a long way. They have almost lasted me a year.

As for the pH adjuster I cant tell from the container what it is made of. Although I do know I have never encountered a problem with them before. I had 32 strawberry's in a 40 gallon reservoir last summer. In another system I had 6 pepper plants, 1 basil plant, 1 mint plant and 1 sage plant all in one 10 gallon reservoir last summer. I now have had broccoli in a 8 gallon reservoir sense last October, I recently (about 6 weeks ago) filled it up so now it's a 18 gallon reservoir. And some recently started butter lettuce that has been using the same nutrient solution for the whole time (a month) that I have never had to adjust since the first day when I started them.

I also have my newly planted tomato plants using 9 gallons in the reservoir for the first two weeks, then I just added another 6 gallons (adjusted pH to 6.0 before adding it) for a total of 15 gallons that will be in the same nutrient solution for a month come Sunday, and I have not had to adjust it at all sense the first day.

The only plants that I have had any pH problems with are my peas. I have had these peas sense last November (I think), and had no pH problems until the last 3 weeks or so. I have been using the same pH adjuster from the beginning, even from the same containers because I have never needed to buy anymore yet. So I am wondering why only now, and with only one plant (system) I am having a problem. The only things I can think of are the plants are drinking up so much water for the size of the reservoir, that might have some sort of affect on the nutrients (even when adding pH 6.0 water back). Or maybe it has something to do with the size of the plants themselves, because since the weather has warmed up a little in mid January, they have been growing nicely until the last 3 weeks.

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