Backyard Aquaponics
A place to discuss aquaponics

Think angie might mean "slaked lime" - "hydrated lime".... Calcium Hydroxide ... that'll buffer toward pH9-pH10....

Tamo, not sure I agree with the mix of grow media resulting in a yoyo affect....

Firstly, all beds will be dtistributing back to the sump (essentially) at the same time or continually...... therefore the sump will mix the respective pH waters from the grow bed drains....

To my mind then, the resulting sump water will be lower than the "acidic" pH but higher than the "basic" limestone water .... exactly what we would be looking to acheive...

Obviously the mixing/dilution would continue throughout the entire system.....

Secondly.... carbonate buffering... using calcium carbonate, potassium bicarbonate etc is essentially doing exactly the same thing....

The carbonate (which we are employing to pull pH up) will only dissassociate chemically when the conditions are acidic enough for it to occur....

When the equilibrium point is reached the reaction stops... until conditions reach a point of acidicy that it begins again....

This is a continuous seemless process... not a drastic yoyo affect.... there's a full explanation in another post somewhere (I'll link when I've found it)

My conjecture would be that the mix of grow media beds would behave exactly the same.... the limestone carbonate would dissassociate (dissolve) when conditions were acidic enough and cease until conditions drifted < pH 7.0 - pH7.5..... then begin again....

Again IMHO... seemlessly and continuously...

I don't think the pH will yo-yo, I do think whatever salt will form as a result of the acid-base reaction could be a problem.

Well my pH seems to be holding steady at about 8.0 :/ I've been feeding my fish as much as they can shove in their faces but the ammonia/nitrite/nitrate levels stay pegged at 0 when I test. The water looks nice and I can see the fish due to the water changes, but I fear that the algae is going to just take over again. I've started the hunt for new gravel. I found some places that sell 'river gravel' but the gravel from the river closest to me has lots of limestone, shells, etc in it. Its amazing how little the people selling gravel know about their own gravel... I'll keep ya'll posted. I tried to talk to a girl at a local fish stoe and I couldnt talk her out of trying to talk me into buying their 'bulk' gravel 50lbs at a time hehehe...

I could be wrong, but I seem to recall that Travis (of barrelponics) uses a pine needle bog in his system to bring his pH down. It's been working for years. I don't know what to say about the resulting salts, though.

Too bad the search function on yahoo groups is rubbish, or I'd look this up and confirm.

Good one ,, yes pine needles are a well know acidifier ,, I use them on my blueberries to assist in getting the PH down around 5. Don't think they would hold much water and they seem to break down very slowly ..... definately worth a try ( perhaps even straight on top of one of the beds you have now).

Pine needles have been know to cause abortion in cows... particularly "Ponderosa" pine...

... and similar reproductive failures in studies with mice....