Backyard Aquaponics
A place to discuss aquaponics

An update and then a question:

My system has 50 1 year old silver perch in the 1000L IBC, and 100 silver perch fingerlings in the 500L sump. The two bathtubs filled with scoria have silverbeet in them which has gone to seed, and that's about it.

I am struggling to keep the pH reasonable. I have 5 socks worth of shell grit hanging in the sump or tank - I use socks or pantyhose rather than adding directly to the bed so I can adjust the pH by adding or removing socks. However 5 socks worth isn't enough to keep it above 6! I see the fish flashing, measure pH, 6, top up the water (tank water is pH 6.9), swish the socks around, add some Potassium BiCarbonate and then they're fine for a couple of days.... then it's back down at 6 again.

The question is how much shell grit do you guys have in your systems to keep the pH reasonable?

Alternately, do you know of any other acidic process that could be going on to keep brining my pH down?

Hi i think you will find most established systems drift down i have 30 kg in the growbeds and it drifts down i just use white builders lime 1/2 cup direct in the sump once a month or when i think of it thats for 5000 litres i would just stick in 1 tablespoon and checknext day

I use a couple of handfuls of dolomite to every 1000L every couple of months. It sits on the bottom of the tank and slowly dissolves...buffers the pH is around 6.8-7 until it runs out and then the system drops back to <6. I think the plants like the extra minerals as well

Would have thought you'd know the answer.. and solution to that one Gemmel....

What do you advise your "clients" in this regard?? ....

20kg and it still drifts down, ok thanks, that puts it in perspective for me.



Emphasis on the OTHER in "other process" - obviously the nitrification process is acidic - but until this year I have only needed to buffer with 2 socks worth of shell grit and this system is coming up to it's 4th year in operation (in march).

My only guess is that any buffering provided by my scoria has now all been used up and I need to bump up the additions of other buffers. And I've also got a bit more of load in there now, so that would contribute/cause as well.

I guess I'll just do it, but I was wondering if there could be something else going on (e.g anaerobic zones, scoria buffering being used up, or some other black magic). Gunna need some more socks.