Backyard Aquaponics
A place to discuss aquaponics

Hi
I have a 2 grow bed system with a 2000L tank, its about 5 months old now and has never been right. I started with 20 marron and 50 silver perch I am now down to 3 marron and about 20 silvers, I have had about 8-9 marron die in the last month.
Vegies are just dieing or not growing. I have a blanket weed issue that was growing about 3 inches a day and I have covered it now with a tarp after cleaning it out and it has slowed right down with reduced light.
The water test all appear normal ph 6.8-7.2, nitrates and nitrates 0
I have started today changing water but not sure how to change, did 70L today which does hot sound like enough but do not have enough buckets. I have filling the buckets and leaving the in the sun for 24 hrs for the chlorine to disapate I hope that is ok?
I have put some crushed limestone in today as well
I was putting seasol on the vegies but has not made any difference, I had put 30ml in a watering can and spread it over the grow beds a couple of times.
I am putting in about 2 teaspoons of food and they seem to be eating it, any more and its on the bottom
The fish were about 30mm long when got them, 3 have grown to about 60-70mm and rest are still the same size.
I think this is about all the info, if anyone have any suggestions that would be great.

Hi smallbrook,

Sounds like you have probably weathered the worst of it I would think. Sounds like your silver perch were very small to begin with, and stocking them at the start of winter, fish that small will be very slow to get going over winter in a new system.

Firstly don't put in any limestone, your pH is good at that level. If the alga is still a problem, keep the cover on, as the water temps are starting to heat up the silvers will become more active and they will start eating the stringy algae, and soon it soon it be a problem any more.

Systems can be slow to get going with silvers over winter, especially when they are that small to begin with. The plants will be suffering because there's just not a lot of input into the system with feed.

Don't change any water out of the system, I don't see any reason to change your water, you're just taking out any nutrient there is in there. Plus Perth water is pretty good, you don't need to bucket the water in, just stick your hose in the tank and top it up when you need to.

Why your Marron are dying? Not sure, marron are aggressive and they will fight for space and kill each other, this may be why.. I would think that 3 marron might be all you can keep in the system long term. Why you have lost silvers? Probably because they were very small to go into a new system at the start of winter, small silvers are prone to problems when water temps are down and they are very small.

I would think that now water temps are on their way up your silvers will be right, their feeding rates will increase, they won't be as susceptible to disease and parasites and with the increased feeding rates your plants will then start to take off..

Yea I agree EB, 20 marron would not co-habitate well in such a small area.

Hi there
Faye at backyard aquaponics has been saying the same thing that will all change soon when water temp goes up etc, but the hatchery of the fish say that I must have a problem because the marron are pretty hardy and should out survive the silvers and they say the fish need the sunlight to grow but the algae will go spastic again.
I have noticed within a couple of days of cleaning the tank out with the algae i would find dead marron so I put it down to the fighting for their hides again but the hatchery did not think they would fight that much
The plants should atleast stay alive I would have thought.
The other thing is that I have barley straw in the tank as I have been told it will help with the algae and someone else said it is an old wives tale. Has anyone had experience with the barley staw.

barley straw will inhibit algae growth, but you really don't want that in your tank..
do you have an air pump into your ft?
dead marron in the tank will cause your ammonia to rise..

So did you get the fish at the same place as the marron? As I said, I think the marron are probably dying from fighting, not because of water quality, you just can't have that many marron long term in a tank that size..

The fish do not need sunlight to grow, well, not direct sun anyway.

I would remove the barley straw, I've personally never used it, and from what I had heard it was useful for suspended algae, I wouldn't know about stringy algae...

Marron need exellent quality water to live or they will walk. Its quite common in ponds or dams that when water quality drops, thay will take off to find a new place to live. Its quite possible that if your algae problem is too bad and they cannot escape, they will be stressed causing aggressive behaviour and deaths.

Yes I got the fish and marron together from the same place and he said 20 would fine as long as they had enough hides
I know that the marron were eating the fish because had seen marron walking around with a fish in their claws and when I disturbed them the fish swam away.
3 managed to get out, I found 1 and put him back and the dog found the other 2

Smallbrook, one thing to note when you are doing aquaponics, take advice from people who are doing only just aquaculture, hydroponics or aquarium/pond industry with a bit of caution. They tend to have a quick fix for the issues they face in their specific industry, but when it come to aquaponics, it is about maintaining a balance so often there are no quick fix. So if you take their advice without caution, you will find that you may be creating more issues for yourself...

I bet you were also told to add some lime into the water as silver perch liked them. If I recall correctly, lime is added because it will cause algae to bloom. Works well in the dam environment because the silvers feed on them, not in an aquaponics environment when you are trying to keep crystal clear waters...

Unfortunately it is hard to know what to do with so many opinions and what I have been doing is not really working.

Keep the tank blacked out to kill off the algae. With a bloom like you are saying the algae will be using a lot of the nutrients you want for your plants. It also upsets the oxygen levels in a way I cant remember this morning

Well let me make it clearer, only listen to people that have done aquaponics themselves.

If my guess of where you got the silvers and marron from is right, I got some from there as well. Similarly I was told to add lime too, but from reading from the wealth of information on this website, I decided not too.

Take on what Earthbound has said.

Out of curiosity, how many hides do you have in the tank? If you had 20 marron, you need at least 20 hides.

Adding to what mantis has said because he cannnot remember, algae is like a plant, release oxygen during the day but absorbs oxygen during the night. This obviously reduces the amount of dissolved oxygen in the water for the fishes. In addition, the presence of algae in the water also swings the pH of the water slightly, as while plants absorb oxygen in the night, carbon dioxide is given off and hence swings the pH of the water from day to night.

g'day smallbrook
I'm up in ellenbrook if you want to drop around for a talk & look at my system that might help
you with some ideas I've got a new pond going through the same thing at the moment send me a PM if you want to come up

cheers Wolly

Yep, algae can cause lots of issues.
I noticed in the first post you said
Nitrate and nitrate is 0 but you never said what the ammonia or nitrite was.
I'm kinda guessing that you meant Nitrite and nitrate were both 0 but still, what about the ammonia?

As to algae. It can be a real problem in aquaponics since it does steel nutrients you want for your plants and it will also mess with pH and dissolved oxygen levels and if it dies off it can cause even more problems if the bio-filter isn't up to handling that kind of load in short order. Once you get some to die off and decay in the grow beds it can help give off some bio-chemicals that will help inhibit future algae blooms to an extent and I think it will work even better than the barley straw. For now, keep it dark and make sure there is extra aeration.

Hi wooly
That would be great let me know when and where and i will drop in