Backyard Aquaponics
A place to discuss aquaponics

How high is too high? How low is too low?

I know that seashells or limestone are good ways to raise the PH if it gets too low, and that PH will sink naturally and can be brought down with seasol/maxicrop or chelated iron, are there other ways to lower the PH? I assume that dumping vinegar in your system is probably a bad idea.

From what I understand plants prefer a lower PH and the nitrifying bacteria prefer a higher PH, plus crustaceans such as crawdads and yabbies prefer a high PH.

seasol/maxicrop and chelated iron don't really do much to bring pH down.

To bring pH down, you need to make sure there is nothing in your system buffering the pH up (if there is concrete, mortar, limestone, marble or shells in your system and you try to bring the pH down using acid you will simply cause pH bouncing because as soon as the acid brings the pH below the buffer level of the material, it will begin to dissolve and the next day the pH will probably be back up where it was before, this is not good.)

Then I would suggest you do some experiments on you source water. Here is a blog post with some tips about tap water and pH http://www.aquaponiclynx.com/ph-and-tap-water

And from there I would suggest that you might set up a container with your top up water and adjust the pH of the top up water and let it stabilize before you use it in the system. This will be much gentler on the bacteria, fish and plants.

Muratic acid, phosphoric acid, or sulfuric acid are probably better choices for adjusting pH than the vinegar. Citric acid is a bad choice since it is antibacterial.

So what levels are bad? I assume this varies a bit depending on what fish and plants you have in your system, but are there levels that we can be pretty sure are too high or too low and are levels that one ought to start worrying at?

What range does you ph tester measure. The commonly used API kit here measures from 6-8.something so if a reading of 6 you dont know if it is 6 or below. Below 6 is thought by many to stop the nitrification process so we try to keep the ph above 6 and below 7.
On the other hand, ammonia becomes more toxic to fish the higher the ph goes.

Very hard to give definitive answers as I think it can depend on other factors like fish species as well.

We have our systems performing pretty well here with pH's below 6 constantly. Many don;t like their systems running low pH's, I'm happy with the results... Though I don't think the Barramundi like the low pH as mush as silver perch, black bream, and trout.

I think the main reason to be careful about running a low pH is that the test kit most of us use only measures down to a pH of 6 (therefore if the pH reads 6 it could actually be way lower and if it drops too far too fast the bacteria can crash and ammonia spike again.) So people depending on such a test kit should keep their pH enough above 6 that they can be sure to take action before the pH actually gets down to 6. If you have other means to accurately check the pH, the if the system balances and works at say 5.8 then I see no reason to call that a problem as long as the bio-filtration is still keeping up.

For the average person using the API master test kit and dealing with harder tap water than not, then I would say a pH of 6.8 is probably going to be the ideal goal. And the functional range is more like 6.5-7.6. If your pH is above 8, you are likely to have difficulty with the plants being able to take up the nutrients they need and you will need to figure out why your pH is so high and if you will be able to adjust the source water pH using acid before adding it to the system or if there is something in the system causing the buffering.

This is what I'm talking about though, the attitude of "I have to monitor so that I can manipulate if I don't like the results". Am I the only person who gets away with making no adjustments to my systems? Are those making pH adjustments really necessary? Yes ok, I know that bacteria can get affected after the pH starts to drop, but if you ride through that drop in the system, it appears to sort itself out. Whether it's different strains of bacteria converting ammonia and nitrites I don't know. Perhaps it's just the bacteria adapting to the changed pH levels, but at low pH the same functions are being performed within the system, nitrification is taking place quite effectively at pH levels that conventional aquaculture literature says that it shouldn't.

Our trial systems down the back were for memory about 5.6-5.8, I am not going to add anything.. Plants are growing beautifully, fish are eating though the temps are just a bit low at the moment so they have slowed down My systems at home used to all be below 6, I never adjusted, well I attempted to at the start, but then gave up. Now they have actually come back up themselves to just under 7 over the years .

I'd like to better understand why this is happening...

Yea I agree EB, I tampered the crap out of my first set up to try keep my PH above 5-ish and the constant swings did more damage than good. Couldnt get plants to grow and my carp bled from the gills. I just leave PH alone now and everything is happy and healthy and to be honest that one less thing to stress about.

I don't own a test kit. I am tempted to buy one so I know what the levels are but that will more than likely lead to tinkering then onto swings with the levels which could lead to bigger problems.

I do have some shell grit in the sump to keep to pH buffered to prevent the nitrification process from dropping it too low. Over time it will dissolve and I will replace it.

Apart from the shell grit, I add some Chelated Iron and/or some Seasol when I notice an iron deficiency or want to boost the growth.

did my first water test today. is my PH anything to worry about, or will it come down naturally? no fish in my system yet.

If that is Tap Water..

you might have the same problem I did..

Run a few air stones in the water for a few Day's.. I found out that my pH finely dropped down after a few days of constant Air running..

Juergen

I have 2 points of airation(is that a word?) in my system, from the GB into the sump, and from the sump into the FT. that should be enough to get the oxygen dissolved into the water? yes it was tap water. my water also has a nice green hue to it, does this have an effect on my PH level?

If you have a small air pump used in an Aquarium drop a few Stones in the system.. That is What I do..

Juergen

My system is running outdoors open air and i'm having trouble with readings. I'm using rain water and my ph has gone up to 8.0 and my TDS is around 275. Any assistance would be appreciated. I think it may also have something to do with the "Viagro" river rocks that I'm using.
Resources here are pretty limited. They also have "Pond Pebbles" and "Red lava".Not sure if they would make any difference.
System can be seen at
http://www.facebook.com/?sk=welcome#!/p ... 3734012989

My water is from a well and comes out of the ground with a ph of about 6, after putting together my first growbed, filling the fish tank and letting it set for a week, I got some channel catfish and after 4 days decided I should check the ph of the water. Wow, it was at 8+ I am using pea gravel (river rock) I'm wondering if it caused the problem. I got some HCL and put in about a 1/8th of a cup for my 500 gallon system. It went down way faster than I wanted it's now close to 6. Fish seem to be fine. I didn't want to bring it down that fast. I guess I should try one teaspoon at a time from now on. I guess if it builds back up to 8+ i probably have a problem with my gravel?? Any thoughts?