Backyard Aquaponics
A place to discuss aquaponics

Hiya Pete, I was a bit surprised that you were getting rt's coming into summer generally they are a winter fish. I've carried rt's through summer a couple of times but without a water chiller and free power I'm not overly keen to do it again, too much stress during our +30°C summer. (says me with trout still in the tank...) Without cool nights it would have been impossible.
A word of advice, don't feed the fish before warm days regardless of how hungry they seem to be, gotta be cruel to be kind.
Good luck.

Thanks for the tip Skeggley,

I'm working on that issue and in the mean time I'll be using other methods to try and keep the fish alive.

We've been snacking on the snow peas and mixed salads which seams to make them produce more so now we have them with our main meals.

Still have 15 trout ranging from 75 - 110 long, have used no additives other than 1 1/2 teaspoons of FF a day and float water top ups.
Got the new shade cloth and fitted some of the polystyrene panels to the stainless with double sided tape and silicon.
The timer has been set at 15 on 60 off 24/7 for the last 2 weeks.

How does the chemistry look?

Pete.

purple and green should never be seen...
yellow and blue - yahoo.....

reckon that should be our AP ammonia/nitrites rhyme.

all looks OK.

pH seems to be gradually coming back a bit but still 7.8-8.
time should sort it out - what is the pH of your top up water ?

Darren I took the rain water sample from the wicking bed PE roof. It's very low compared to the tap water.
Why will the ph come down over time?

Pete.

A lot of natural processes tend to leave systems with acidic by-products plus things like carbon-dioxide etc.
Nitrates will actually pull the pH down a bit as well. High nitrates can give a pH drop (and also increased EC response).

So if you had a closed system without adding any additional water eventually the natural buffers (bicarbonates, carbonates would break down - these are most likely what is keeping the pH up - in your case it is not the media).

In nature without the presence of geology or similar soil/mineral presence it is hard for systems to be alkaline.
Rainwater tends to be slightly acidic (CO2 plus other airborne particles).
Systems with high iron etc for example tend to be acidic, sulphates etc etc

So an AP not having media or tap water inputs to buffer will basically drop in pH over time.

your rain water sample is on par. Rain water (and RO water for what its woth) are normally 6-7 and usually around 6.5. Those of us with acidic systems 6.5-7.5 note a drop in pH over winter as rain enters the system.

[edit] if you introduced rain water gradually into your system instead of tap water it would get to 7.5 quite easily provided there is no media buffering affecting the pH.

As the table below from the Troutmans website says the comfort level up to 24 C is Ph 8.5 so should I be using rain water to top up instead as it's so close to it?

Pete.

the 7-8 range ticks more boxes.... (also for the plants as well)

Pete, great system. Nicely done and thanks for the thread. I would like to keep trout or salmon someday and your experience gives me hope. My area is too cold for tilapia in the winter and too hot for trout in the summer.

I raise channel catfish in my large system since they can take hot or cold, though they don't eat in the winter. I have tilapia in another system but right now my heater is on 24/7 and barely keeping the water warm enough. I thought they would all die last week when the water dropped to 63°F (17c). In the summer my water gets up to 80°F (27c) or higher.

What's the ambient temp outside the tank in the shade when it gets to 27 C?

Pete.

Summer days are typically 30 - 35c in the shade.

I have a fish behavour change.

Up until the last few days the trout would hang out mostly at the bottom or in the lower half of the tank. Only when feeding would some come to above half way. The temp has been between 11 & 18 C and chem as per previous post. The only thing I did back then was use a 20 mm hose to vacuum out the bottom of the tank, maybe I spooked them.

Since then they have been real cagey - like I was going to eat them or something???? They'd hide in the upper back half of the tank, wouldn't come out to grab the feed as usual, didn't seem to consume as much food that fell to the floor. I have been leaving the hatch shut more than usual and though it might be better to have it open so they don't get suprised when it does open before feeding times.

Yesterday I snuck up on them to see some of them playing and splashing at the surface while the others were slip streaming just below the surface at the side of the slo and rear of the tank where it's hard for me to see them. I though that maybe they needed more oxygen so I turned the bubbler up to full from 60%. While I was messing with that I disassembled the SLO so I could increase the flange height above the floor to 7 mm. The fish were zipping all around the tank while this was happening.

Any thought on this ?

Pete.

Probably spooked from the bubbler and SLO activity. I think it's a good sign that they are active/normal when they don't see you. Trout have excellent eyesight and will spook at anything that could be a predator. Maybe instead of a bubbler you could use water circulation for better aeration, like a spray bar, or fountain type device. I use a 6 watt power head a little below the surface and pointed up to make a surface disturbance, but without the aggressive noise of a bubbler. It also helps draw water from the bottom of the tank topside for aeration and helps the circulation in general. Tests with my DO meter show the power head is much better at providing DO than an 18 watt air pump / bubbler.

most likely they are responding to the additional light 'warning trigger' - having associated it with the appearance of a monster that upsets their nice sedate lifestyle... obviously the moving around and probably banging/knocking on the FT sides and wall. takes a long time to build up trust via food and not much to send them paranoid again.

are you monitoring your during day water temp fluctuations ? May be worth getting a recording probe.

It looks a little darker now but 5 minutes after the test the nitrates were yellow. Does that mean the GB's are consuming everything the fish tank can produce? Should I add a cap of Power Feed? Fish are still splashing and hiding but I noticed the feed at the bottom of the tank was gone.

Pete.

>> Should I add a cap of Power Feed? Fish are still splashing and hiding but I noticed the feed at the bottom of the tack was gone.

not to the fish tank (IMO *never* to the fish tank). I would only worry if the plants suggest they need it.
If not don't bother and perhaps just use some seasol normal direct to the grow beds.

your ammonia is low so everything is working. The load will increase as the fish get bigger.
one option is to put a little blood&bone with potash lightly on the grow bed and then gently water in.
then just water every few days. It will feed the plants and act a sa slow release with most likely to stay around the plant roots. B&B with PA will add N, P and K and will be a bit more gentle than Power Feed.