Backyard Aquaponics
A place to discuss aquaponics

I am discovering something interesting in my system. The pH has dropped from it's normal rock solid bottom pH of 7.6. I have measured as low as 7.2 and even a touch lower lately (and that was taken late in the day so this isn't pH fluctuations from algae or anything like that.) My system is full of sea shells but apparently with a year worth of maturity, a few heavy rains, and some regular dosing of iron, my system has a lower pH now.

I will have to watch it closely as if it falls below 7 and I have to do any major top ups with well water, it could cause some major pH shock for my bacteria, plants and fish and I'd rather keep the pH as steady as I can without having to add daily buffers.

I just thought it would be worth while to note that even if your starting system pH is between 7.6 and 8, don't stress about it. That is a fine range to start with, I did. In the early days of my system, I had trouble with iron deficiency and that is mostly due to chleated iron not being as easily available around here (and what is available is quite costly.) Now days I still see some signs of deficiency and I dose a bit when I do but the plants are generally doing much better this year.

Have you noticed a reduction in the bulk of the shells TCL.. i.e they've dissolved (partially)... thinned, or even broken up...

Could be the total amount of buffering capacity has decreased over time... and the rising acidicy is consuming more in a shorter timeframe... decreasing the buffering capacity further..

I did notice that the level of the media in the beds had gone down and we topped up with more gravel. I assume that a % of that level drop is simply due to media settling as it does but I also suspect that the shells have been breaking down over time. I'll probably want to get a few bags of shell grit to have on hand for the system as well as for the chickens.

I also suspect that a certain amount of the buffering capacity of the shells is sealed up under a coating of bio-slime and will only be effective when I dig into the beds and disturb that bio-slime coating.