Backyard Aquaponics
A place to discuss aquaponics

Hi We have just started the whole aquaponics craze and were excited...not so now!!! We are using blue metal for the growbed but washed this out well... and I mean well... 1/2 tonne blue metal takes 5 days to wash!!! grrrr

We got silver perch fingerlings last Friday and they have been going ok but the last couple of days they have been dying and we lost 11 today!!.

We check the water every day and seems pretty settled. pH has settled to between 6 and 6.4, Ammonia is between .25 and .5, Nitrate 2 is at 0 and nitrate 3 is at 0

The only thing we could put it down to is the water temp which is sitting at 32 deg. Our problem is that the heat has only just started and it is going to get way hotter here and so we need to find a way of lowering the water temp.

Can anyone offer suggestions...1) why our fish may be dying and 2) how to lower water temp.

Thanks

Michelle
Newman
West Oz
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Hi Michelle,
We need to know a little more about your system. A photo would be great!
Size of water tank and growbed area.
How big are the fish and how many?
How much are you feeding and what?
How much are you pumping the water?

If you think it is the heat, can you rig up a shadecloth cover?

I would check to make sure that there is nothing on the bottom of the fish tank eg uneaten food, leaves etc!
Have you added salt? If not do it now. You can add 3 parts per thousand of straight pool salt, strawberries won't like it but most other plants tolerate those levels. Salt is to fish like seasol is to plants.
Has anything else been added to the water?
Any contaminants, sprays etc in the area!
Sorry for the interrogation, I am just trying to understand a little more.

Thanks Faye...ummmm... lol most of those questions will have to wait until hubby comes home.

We have a 1000lt IBC which has been cut. so the fish tank is about 700lt and the grow bed 250lt

We did have 50 2cm silver perch but now have probably 38

There isnt anything on the bottom of tank, it is pretty clean

The food is the only one I could get here as I forgot to order food when I ordered the fish..duhhh and we only have a Woolworths.. so it is called Marine Master Goldfish Granules and the ingredients are fish meal, shrimp meal, wheat germ, wheat flour, soybean meal, yeast, vitamins, organic minerals, natural colouring

Sorry not sure how to post a photo

Not sure how much we are pumping but it is taking 15 minutes to fill grow bed

There is shadecloth over the top already

The pH went up to 7.6 so hubby put hydrachloric (??) acid in. He didn't put it straight in but mixed it and diluted it first.

Haven't done the salt... what does it do? And would you believe the only plants in the grow bed at the moment are strawberries..lol

No sprays or anything like that used anywhere near us.

We are a bit worried about the water temp as it is starting to warm up and it isn't unusual for us to 45 and over for the next 4 months.

Thanks for your help

Michelle

Hi Michelle,

I think you need to consider Barramundi... Like Wal in Tom Price.

Yeah we did consider them and a friend here has them but we thought that the fact they eat each other and have to be pretty much the same size and other things hubby read about we thought the perch was going to be easier...hmmm!!!

Might have to chase up this Wal in Tom Price...lol

We were also looking at getting Marron but not sure about that one either

Thanks

Mr Damage

New fish settling in...
The heat - 32 for extended periods will kill them.
Part of the issue will be the blue metal it is a great heat sink.

Try to increase the flow rate in the fish tank through the grow beds and perhaps a lighter colored gravel on the top layer of the grow beds.

yep of course never thought of that, wasnt even giving the grow bed a thought. We are going to go with the clayballs for the rest of our beds we think as I am NOT going to wash that damn blue metal again...lol

You can top dress the beds with clay over the top of the blue metal if you like. That may reduce the cost.

Will suggest it to hubby, he is driving down to Perth soon. The cost wasn't a huge factor with going blue metal, we wanted to try something different and it was readily available here. Mind you the fact that when I got a quote for the clay balls and they were $35 a bag and another $45 per bag for freight did kinda tip us to the blue metal...lol

Thanks Earthan Group

We are soo new at this that we appreciate every bit of advise

Cheers

Michelle

No worries.

If you buy a fair few bags, most places sell at around the $30 mark per bag. I just bought 120 bags at $24/bag (inc. GST) around three pallets through a retail hydro store (need another three lol) and the freight was $286 from Victoria to South Coast NSW.

The blue metal is exellent as it contains around 60 odd minerals that really benifit the system in comparison to inert clay media. Good to throw a layer in the bottom 50mm of the bed and a layer of shade cloth, then your clay media on top of that..

Why do you recommend the layer of shade cloth between the two media EG??

Keep them separate when washing or harvesting etc...

I don't quite follow you EG... especially in relation to harvesting... wont the roots pass through the shade cloth between the layers anyway??

If you fill a bed with a mixture of media, if will over time, get all mixed up. This will be why the shade cloth has been suggested.

Ive run gravel with hydroton top dressing in my blue barrel system for years... and not found this to be the case really at all...

To the extent that when I recently moved... I was able to virtually seperate and move the two media independently...

Admittedly, I did mix some of the media slightly when I removed a tomato plant that had been growing for over two years...