Backyard Aquaponics
A place to discuss aquaponics

Hi. We have a relatively new 4 bed system, with a 3,000 litre inground tank. After filling the tank with half rainwater and half tap water we planted all 4 grow beds. The original pump we bought was too strong so we bought a smaller one which we later discovered was filtering our fish out of the system. Before any fish went into the tank we allowed over a week for the water to settle. When we tested the water the readings were as follows.
Nitrite - 0 ppm. Nitrate - 0 ppm. Amonia - 0 ppm. Ph - 7.5. When the High Range Ph was checked it was found to be 7.4. Temp range 16 - 20`c.
We tested the Tap water and found exactly the same readings. After a week the readings had not changed. Our first batch of 100 Rainbow Trout 4 inch fingerlings were destroyed partially by the Pump. We skirted the pump with a mesh. Our seccond lot of 100 Rainbow Trout 4 inch fingerlings over the last 4 days have mostly all been found dead on the bottom of the tank. Subsequent water checks show no change in any of the readings. Can anyone suggest anything.
We put 4 koi (3 - 4 inch) into the tank, they are doing great.

Hi Lynn&Henry and welcome to the forum

Sorry to hear of your fish losses. Can you give more details on your system like grow bed volume, type of media, flood and drain or CF? Also are you using any type of aeration?

I think it's a 4 bed BYAP "Family" system Charlie....

Whereabouts are you located.... and what have your tank temps been over the last few days??

And when did you get the last lot of Trout??

We are located in Perth Western Australia, although ambient temperatures have been in mid to high 30' celsius, Tank temperature has been between 16 to 20' c. Tank is inground and is shaded by the growbeds and a walkway. with 4 500 Lt HDPE Growbeds. We are using Hydroton Expanded Clay, We have used it successfully in our Balcomy unit in the past. Tank Temp has been fairly consistant as have the readings. Our first lot of Trout were purchased 5 weeks ago, this second lot of trout was purchased 11 days ago. I have suspiscions that the ph has a lot to do with it, I am looking into rying to reduce the ph. The fish farm has a 0ppm ph as they have river water available to them and they were exceptioanlly healthy. The first fish died wbout 5 days after purchase, we have lost the bulk majority over the last 4 days.

I take it that the trout farm has a neutral pH... 7.0 ... so your 7.4... shouldn't have worried them...

Have you tried testing the temperature with another themometer?

Yep... those temps certainly seem a bit low... even allowing for some thermal insulation from being buried...

Aeration?

I can't help thinking that now is not the time to be trying to grow trout, our summers are not easily compatable with the temperature that they like. Not sure when you are testing the water temp but I suspect if the growbeds are in the sun the water would be heating up and peak in the middle of the afternoon.
Are you able to post a picture of your system?

Lynn,
My system is extremely temperature stable by design, under cover and concrete tank plus in ground sump.

Despite this current water temperature is 26.5 deg, max temp this week has been 27.5 deg. Note that this measurement is taken from the bottom of the tank not the surface. Bunbury is not too different temperature wise too Perth.

Unless you have a very deep in ground tank I would think your temperatures are a lot higher than noted.

Edit: How far were they transported as well. Kept cool during that period?

From what i've read 26.5c - 27.5c is probably to hot for trout.
Maybe add some large ice blocks...

As we have the 4 Grow Beds siting above the tank [ /] [\ ] 2 grow beds
::(::::):: Walkway across the middle above tank.
[ \] [/ ] 2 grow beds Tank below the lot.
The grow beds drain directly into the tank, giving it good aeration. The Tank itself is a 3,000 Lt Plastic moulded tank we have settled into the ground leaving 30 cm above ground. I will get some photo's and post pics of the system. We are now down to 3 rainbow trout after I fished a further 11 out this morning.
I have pipes hooked up to the drain pipe waiting for rain. but, you know, miracles happen everyday, the impossible takes a bit longer.

We get our fingerlings from Golden Ponds 10 minutes drive from home. once we pick them up, we put an aerator into the water and get them straight home. With so many fish, we have to place them straight into the tank and they were doing well for the first few days. Temperatures between 14 to 20 degrees c, I have been told is OK for trout, anything over that is too much. But I have been checking the temp through the hot days, and it hasn't raised above 20`c. So technically, the fish should be fine. Maybe I just haven't got a scaley thumb and might need one. I haven't got a green thumb either, but the plants are surviving.

Have all the fish came from the same source..?

If they have not you might of Killed them because they got a Bug that they were not immune to..

Juergen

I'd be looking at a combination of high temp and not enough aeration.

My Trout didn't like it past 23 deg C, in a small above ground tank, temp measurement was on the surface. I have two large air stones for aeration. I also only had 10 Trout.