Backyard Aquaponics
A place to discuss aquaponics

simon as a more longer term solution, go get some shell grit (coles selss it) chuck it into a panty hose - not one of your personal ones that you save for special occasions- rinse and then put it into your system. tie the end of the hose onto the ibc cage and just leave it. It will dissolve....eventually... and stabilise the pH at about 7.4 ish. I had a similar problem with my first system, pH got to 7.8 from memory, didn't panic though, just did the shell grit thing and after about 3-4weeks, got down to 7.4 where it has stayed ever since.

Vinegar , fish and chips ,, sounds like a natural:)

Quachy, just to clarify, putting in shell grit won't bring the pH down. Nitrification is an acidic process, so pH goes down as Ammonia is turned into Nitrate. Putting in the shell grit will buffer it at 7.4ish but you still need that nitrification process to bring it down.

My concern is that it's 8.0 in the first place. If the water source is 8.0 then every time you top up your system you're going to be messing with pH.

Probably not related to your current issue, but do you have only just 100L of growbed as filtration for 50SP??

I thought shell grit would dissolve if the pH went either way of 7.4?

just a quick note.
if you cut a 1000L tank down to 600l - 700l, and you use the rest as a grow bed, wouldn't that mean that you have at lease 300l of GB??

still need more GB but that will hold you for a while till you can double it. May be cut up another IBC into 2 300l beds. May need a 200l sump though,

regards

matt

Okay, see why i was confused before starting this thread. Everyone has different methods and suggestions for fixing certain problems. Im attemping to upload my photos now. But here were my test results.

PH : 8.2
amonia: 0 - .25
nitrites: 0
nitrates: 0
temp: 22C
water volume : 550ltrs

I then added some hyd acid (10ml) and am planning to test PH again tomorrow morning. Should I carry out all the tests or just the PH? From my obvservations today I would say everything is working fine appart from my unusually high PH level. My PH has always been high and i'm starting to assume that we have quite a high PH level in our tap water in Lancefield VIC.
The prototype always had high PH also but I do not test that system much at all anymore as things seemed to be operating sufficiently. No fish kills in either system for me yet too (touch wood.)
I'll get back to uploading photos and shut up for a while.

Just test your pH... the acid wont alter the other values.... unless it kicks the nitrifying bacteria in a bit more... in which case it will merely diminish your ammonia to zero... and maybe raise a trace of nitrates... either way... nothing to be concerned about...

On the matter of shell grit (Calcium Carbonate)... it is a self regulating buffer (a self regulating chemical effect)....

It will only start dissolving when the system is acidic enough for it to do so... 6.8-7.2 (roughly)... and cease... 7.2-7.4 (roughly) once the carbonate has mopped up the acidic ions...

For those that really want to know... CaCO3.....

Not an overly "soluble" substance in itself.... however in an acidic solution, such as a carbon dioxide rich water (carbonic acid) it will dissociate into a "bicarbonate" salt... (indeed Calcium Bicarbonate is essentially carbonic acid)....

CaCO3 + CO2 +H20 => Ca(HCO3)2

A bicarbonate salt has extremely weaks bonds and readily dissociates, as we know... it buffers, ceases at a certain pH as it dissociates... and as it dissociates it acidifes.... breaking the bonds and providing more buffering etc... etc....

HCO3- <=> H+ + CO3(-2) .... (buffering carbonate)

(2 x ) H+ + CO3- => H2CO3 (carbonic acid / bicarbonate salt)

H20 + CO2 (dissolved) <=> H2CO3 .... etc, etc ...

So the CO2 dissolved in water is in equilibrium with the carbonic acid salts.... and in the process "mops" up any free O- ions (dissolved)....

Resulting in dissolved O2 + CO2 being basically in equilibrium....

No nitrates.

could be a reason why your plants have yellow leaves?
have you ever had a nitrate reading? (or a nitrite)

regards
matt

So rupe,
It acts sacrificial ions ???

cool
thanks for the physics lesson.


regards
matt

Having trouble posting my picture and getting very frustrated. I've resized them all. but It still doesnt seem to like me!

3rd time lucky

and another one

one by one theres got to be a better way