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-   -   PH goes Down (http://www.hydroponicsonline.com/forums/showthread.php?t=2390)

simon 04-15-2012 01:54 PM

PH goes Down
Hi everyone. I can not figure out why my PH every 3 days or so bottoms out. It goes from about 6.5 to 3.5 in three days. This has never happen before. I have a deep water system that i use to start tomatoes, peppers, etc before transplanting to coco dutch bucket system. Thanks for any help

GpsFrontier 04-15-2012 11:27 PM

1. How are you testing your pH (meter or drops)?
2. What ph adjusters are you using?
3. what nutrients, and/or any additives your using?
4. What growing media are you using?
5. What water source are you using?
6. Is the water level the same every time you test the pH? Or are the plants drinking water, lowering the water level?
7. if you need to add water regularly, are you adding pH adjusted water?
8. Is the pH the same in the bottom of the bato buckets as it is in the reservoir?
9. How much water does your system hold total (both the reservoir and buckets combined)?
10. How does the water look, is there anything growing in it?
11. What's the pH of the water before you add the nutrients?

hammerpamf 04-16-2012 09:52 AM

Likely factors - water consumption, unstable pH buffers, nitrogen source
As GpsFrontier points out, there are a large number of possibilities to your recurrent pH fluctuations. To me, the likely culprits are:

(1) Most-likely: WATER. Depending on the number of plants and their maturity in the system, they are probably drinking water at a much faster rate than taking up the nutrients. If your temperatures have been relatively-warm lately, that would increase the speed of this dynamic.

(2) Moderately-likely: BUFFERS. If you are using additives to adjust the solution pH, the buffering capability of each differs widely as to how long it can hold your solution at a target pH. It is possible that some chemical(s) in your nutrient solution or additives are unstable and lose their ability to buffer the pH after three days.

(3) Least-likely: NUTRIENTS. All nutrients are consumed at different rates, nitrogen being one of the fastest. However, this depends on which type of nitrogen you are using (i.e. urea, ammonium, nitrate) and the temperature of your solution. If you are using a mixture of these types, the pH will naturally fluctuate regardless of the addition of buffering additives and temperature as each is consumed at a different rate and urea breaks down into ammonium and nitrate.

That said, I would recommend that you start your diagnosis with a calibration of your pH testing equipment/method; proceed by trying to analyze one possibility at a time (I know this can be difficult given the interdependence of all these factors). Standardize your water level, top off your reservoir before testing your nutrient solution pH/tds/ec, and check out the composition of your fertilizer (esp. nitrogen).

Of course, I could be completely wrong - my wife would tell you it isn't unprecedented.:)

simon 04-16-2012 04:58 PM

Hi guys, I use drops to test PH. I tried about everything until i looked closer into the system and saw some yellow algae/mold growing. I just today took the complete system apart and gave it a good cleaning with bleach and then lots of good clean PH 7.0 water. It is now out in the sun drying off before i fill it and start over. I probably should of cleaned it this past winter, but I had lots of pepper plants growing. I flushed out everything down to the air hoses. I have a feeling that may had been my PH problem. Thanks for the help!!!:D;)

hammerpamf 04-18-2012 08:23 AM

Good to hear you identified the algae/mold growth and are cleaning your system thoroughly; however, I'm still not convinced the growth (if it is algae) would cause your pH to consistently drop from 6.5 to 3.5. Typically algae raises the pH of a solution by consuming nutrients and carbon dioxide; decreasing pH more-likely points to either a water or buffer problem.

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