Backyard Aquaponics
A place to discuss aquaponics

Hi Juergen
No - not a heat issue. So I am down in deep south of Tasmania, and I live on top of a hill. The grow beds are in a hothouse, but there is a tarpaulin on the north eastern side. the fish tank is half buried.. even on the warmest day, the water is still very cold.

constant pump.. with bell siphons.

Just an update,
I have contacted an environmental lab down in Hobart who are sending me two sample jars. I'm going to get my fish tank water, and my normal rainwater tank both tested for metals. I'll post the results. Half of me hopes there is no metals - so I dont have to change my setup. But then I'll still be without an answer. If no metals, i'll probably send another sample to the same lab for fish pathology.

Talking to the lab person, I've also had to consider the possibility that something on my roof is causing the problem. I konw that we have some parts of the roof with flaking paint so it will be instructive to see whats in our drinking water as well..

I'd say it's far more likely to be something coming off the roof rather than the tanks themselves. I have seen some very strange coloured algae growing on the silicon joins in corrugated tanks, and yes, it doesn't come off, it's like the algae grows into the thick silicon but doesn;t grow anywhere else on the inside of the tanks, must be something in the silicone..

whats your advice earthbound?

Get your water tested, as you are doing... Do you still have fish in the system or did they all die? If all gone, stick a few goldies in and see how they go as the "canary in the coal mine". Go from there... There's no way you should have to scrap your system, I have two metal systems at home made from the same material, probably about 6 and 9 years old or there abouts, we have a metal system here, and have installed a few of them for people... Yes you go get some weird algal growth on the silicon but I think your system should be ok and it will probably be an external contaminant or something totally different.

Thanks Earthbound - that sounds promising. I'll keep you posted on the water results.