# what causes the PH in resevoir to go down?



## MrPuffAlot (Jun 13, 2008)

recently my PH in one of my resevoirs has been going down.
Been using PH UP to correct.  

im curious, if im having any issues.. or is this normal?


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## massproducer (Jun 13, 2008)

bacterial growth, e.g root rot.  Beneficial growth will stablize the rez at around 6, but bad bugs will cause a drop because they excrete acidic enzymes.  But it be other things as well, but usually a constantly low ph is from bacteria.

What type of system and what are the temps and ppm's


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## gcarlin_818 (Jun 13, 2008)

you always want to go down if you keep going up you do have a problem


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## massproducer (Jun 13, 2008)

not really, if your ph stays too low and doesn't naturally drift up to around 5.9/6.0 in hydro then Mg will get locked out.  You will add more mg in the form of epsom salt and then that locks out calcium


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## Growdude (Jun 13, 2008)

Ive seen this when its time to flush, If the PPM are rising then the PH will fall.


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## Puffin Afatty (Jun 13, 2008)

MrPuffAlot said:
			
		

> recently my PH in one of my resevoirs has been going down.
> Been using PH UP to correct.
> 
> im curious, if im having any issues.. or is this normal?


 
_when a less acidic or akaline component is used the ph will change..If water evaporates the tds increases and the ph can change.  If the nute component absorbed are more akaline than acid the nute ph will go down and vice versa.  :hubba:_


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## massproducer (Jun 13, 2008)

While this is true that ph changes with things like evaporation, this will USUALLY lead to a lower ph, as the nutrient salts gets more concentrated within the solution.

As well with normal eating the reason that the ph will rise is because most elements need a slightly lower ph then 6 in hydrponics, there are only 2 elements that need a higher ph too be availible, those are Magnesium and Phospherous.  Both of which are reqiured very heavily by yours plants but not nearly as much as nitrogen and Potossium which are both lower your ph.

So your plants should eat the N and K, and as this dissapates the PH should slightly rise as the slightly more alkaline elements will still be present in the solution

I basically only grow hydro and i see a chronically low ph in two circumstances

1) Bad bacterial growth
2) Excess Salt build up in rez or at the plants root zone


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## KGB30 (Jun 13, 2008)

You know your stuff thats for sure I am glad MP has you as member to help us newbies & long time learners. Thanks           






			
				massproducer said:
			
		

> While this is true that ph changes with things like evaporation, this will USUALLY lead to a lower ph, as the nutrient salts gets more concentrated within the solution.
> 
> As well with normal eating the reason that the ph will rise is because most elements need a slightly lower ph then 6 in hydrponics, there are only 2 elements that need a higher ph too be availible, those are Magnesium and Phospherous. Both of which are reqiured very heavily by yours plants but not nearly as much as nitrogen and Potossium which are both lower your ph.
> 
> So your plants should eat the N and K, and as this dissapates the PH should slightly rise as the slightly more alkaline elements will still be present in the solution


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## MrPuffAlot (Jun 13, 2008)

im using DWC hydro method.

got one plant in a 2gallon bucket at 800ppm.
did a resevoir change 2 days ago and now PH is solid, hasn't moved down.

got 2 seedlings and 4clones in a 6net pot dwc 4 gallon set up.
Did a resevoir change ysterday and 400ppm.
This morning i check the PH. it was down to 5.39
only took 2 drops of ph up to get it to 5.6.

You can see it on my grow journal.  ie:  amazing race..  

SO let me get this right.

If PH drifts up.. its normal and good.

if PH drifts down.. somethnig wrong and bad.. need res change??

thanks for all the help guys.


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## massproducer (Jun 13, 2008)

Well being that your plants are only babies and are more concerned with growing roots then growing foliage, it is very possible that at this time your plants are eating more P, then N, with would cause your ph to slowly lower.  This is normal, but as your plants grow the need for N and K will increase expontentially, thats when it would not be normal for your ph to be staying that low.  But I did not know that your plants were only babies


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## MrPuffAlot (Jun 20, 2008)

Just adding Keywords, so if someone searches they can find this:

Low PH

PH down

PH unstable

PH help

I think i found my problem with my PH, raising lights, keeping res topped
trying to lower temps.. and going from 24/7 light to 18/6.

For all you future growers..  Nice read:

http://www.icmag.com/ic/showthread.php?t=83605&highlight=low+ph


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