Backyard Aquaponics
A place to discuss aquaponics

Thanks Mr D, I will back off on the iron chelates and seasol. I mixed some fresh woodash with water and used the clear liquid after it settled to adjust pH up from 6.4 to 6.6 today - its strong stuff which I use to cure olives. It should add some K. I have some ecofungicide which is 95% potassium bicarbonate, but I'm worried about the other 5% which could be surfactants - will this hurt my fish

Scotty, years ago (decades ago actually) I worked at a wastewater research station where we were testing adding sugar to lab scale sewage treatment ponds to aid nitrification/denitrification, I was the junior labrat feeding the lagoons with dosed raw sewage twice a week and analysing all the samples. Where I currently work, the Parks crew have been applying sugar solutions to help with transplant shock for advanced street trees - it worked really well until a batch of sugar solution fermented in the tank and the resulting alcohol killed a bunch of trees in my town. I might hold off on the sugar if it favours heterotrophic bacteria over the nitrifhing bacteria, but it would be interesting to see if it helps in AP

I might get a couple of punnets of cool season seedlings to squeeze in to sop up some N - celery, kale, broccolini...

I phoned the manufacturer a couple of years ago to ask, it's 94% Potassium bicarbonate, 6% surfactants. I think it's best reserved for foliar applications, rather than using it to buffer/add K to the water. It is hideously expensive too, shell grit CaCO3 is a much less expensive source of carbonates, and Potassium hydroxide is a much less expensive source of Potassium and a faster acting neutraliser, but you need to be careful handling it, and not tip too much in. ATM I'm typically adding 10 or 20g every day or 2 to my system with all the fish, ~alternated with builders lime Ca(OH)2.

thanks Gordon, I asked about builders lime at the local hardware store yesterday and they only had 20kg bags so I am holding off until I get to a bigger store with more options. I have a tray of shellgrit in my ST and put in a block of limestone under the siphon outflow.