Backyard Aquaponics
A place to discuss aquaponics

I have a simple single IBC system which has been in operation for about 18 months. On change in temperature I get a numerous fish deaths (goldfish).

My current theories are that it is linked to two factors - pH and aeration.

My pH is 8.3 which is higher than I would like. When the system was new it started around this level but dropped to around 6.5 after 8-9 months. After this time it has slowly increased to its current level which now seems to be stable. Media is Hydroton so there shouldn't be any buffering. I have added sulphate of potash, Iron chelate and Seasol periodically but none has been added for a few months now.

I have never had anything but passive aeration in my system. Planned improvement has been to add another power point so I can add some air stones.

My thinking is that high pH and low aeration are stressing the fish such that they are susceptible to changes in temperature. Most problems are with temperature rises but some deaths have occurred with cooling as well. I live in Adelaide, Australia so summers are hot while the winter temps are not too bad.

Thoughts and suggestions appreciated.

Thanks,

Hi
I have a similar single IBC system.
Nothing is worse than watching the thermometer climb knowing it will kill your fish.
Slow the temperature swings by adding insulation. I retro fitted a ‘tin foil sandwich” and scrap bubble wrap. My space is limited.Other better insulation materials are available.
Run your pump more at night for cooling or more in the day for heating.
Warm water holds less O2 than cold so a solar oxygenator helps on the hot days.
Shade of course.
If possible increase you water mass.
Adding frozen plastic bottles of water dos’t do much but cannot
do any harm. It keeps you busy.
Good luck
Titus