Backyard Aquaponics
A place to discuss aquaponics

Hi, It's been a long time since I popped up on here but I have a problem
3 year old BYAP 3 grow bed system, that has been in continous production all that time, healthy long living plants, but the fish are dying!
I have a good growth of algae at the moment but that happens every summer
I have had trout, silvers, goldfish over that time with no issues, having had enough of food fish, the rising temps in October always get the trout before we do , I thought I would go for Koi.
I picked up a 1/2 dozen or so mixed sizes, they did well for a couple of months, so I bought some fingerlings and added those in, they went well for a few weeks, however !!!
The Koi have all died off subsequent additions of goldfish die off 1 or 2 a day
Tested all parameters with 3 different test kits, all good, the only paramter off the scale is GH
Hardness,
The system has always been filled up direct from the scheme water
I set up a smaller tank adjacent filled this with the tap water, and aerated it and pumped it independently before adding it,
Best research I can come up with is rainwater or peat filter?
Howver no rainwater tanks set up, or peat available out here in country WA to filter the water
What can I do to get the hardness down?

What are tyour values for pH.. and hardness??

Hi Rupert, PH across the 3 kits ranges around the 7-<8, the GH is up around 20 drops, should be <10 according to the kit instructions?

PH and GH are related to each other.
If you add acid to the tank, the PH will drop, bringing the GH with it.

If you think about it, low PH is acidic, one of the reasons our water is hard out of the tap is due to the limestone increases the carbonate hardness (kh) giving a high general hardness (gh).
Acid reacts with carbonate, neutralising the two.
So acidic water will have reacted with all the carbonate, lowering the hardness.
Hard water will have reacted with the acid, neutralising it, increasing the ph.

Andrew

Cheers Andrew, What product is the best as an acid, pretty sure the half bottle of sulphuric in the motorbike shed isn't what is meant??

I'd use Hydrochloric acid by preference.... you can get "Diggers" HCl at bunnings...

20ml in 1000L... will move your pH about 0.2.... which is enough in each step...

But each time you top up with carbonate hard water... you'll push pH back up again...

So treat your top up water... not your tank... and along with nitrification... your pH will drop over time...

Sulfuric no, but hydrochloric can be used.
Remember high school chem?
CaCO3 + 2HCl => CaCl2 + CO2 + H2O.

Just use small amounts at a time
And remember, CO2 is more soluble in water than O2, so make sure there is plenty of aeration when adding acid otherwise you can reduce your DO levels.

However, now that I have fully read your thread Koi dont like high heat, they will be unhappy above 25 degrees and will start floating above 30.
Whats you tank temp like?

Cheers team, I am cleaning some of the algae out and running the pump 24/7 at the moment, will get it settled back down and do another test,
Will be back with an update

Thanks for the Koi temp tip