Backyard Aquaponics
A place to discuss aquaponics

Hi Guys,
I posted a few questions i had regarding my system on another thread and Rupertofoz, asked me to start my own thread so here we go.
Im having a few issues.
First issue is my growth rate seems really slow even though my nitrates are consistanly 10 - 20 ppm. and secondly, im losing fish. Not alot in 1 go, but maybe 1 or 2 a week on seperate days.
I got the fish as fingerings in January, and all was good to start with i didn't lose any about the end of march i lost 1 and have been consistanly losing them since. So far i think ive lost about 15 - 20 out of 100. The ones i have lost look perfectly healthy (aside from the fact they are dead)
My growth rates are pretty poor too, i planted some comparitive plants in Dirt and they are about 3 - 4 times bigger in dirt than my grow beds. I think i may be cycling too fast, but anyway ill put some data and pics below, any help or tips would be great

Salt = 1kg/1000L (did have up to 1.8kg/1000l)
PH = 8.2 (has always been around this)
Ammonia = 0.12ppm (most of the time is 0 has been 0.5ppm once a while ago)
Nitrates = 10ppm (normally 15ppm has been as high as around 30ppm)
Nitrites = 0ppm (always is 0 was once 0.25ppm)
Temp = 18`c (did get as cold as 13-14) ran water through some black poly pipe and have heated it back up. Today got it up to 20` Iam hoping to heat it to 20 - 22 over winter via the poly pipe and thermostat pump.
Flood and Syphon system.
Fills in 4minutes drains in 1:20sec. so every cycle only takes 5:30.

Tank will hold 4500L but was running at about 2000L for most of summer. Had filled to about 3500L but this was after the fish had started dropping off. Didn't reduce or increase the issues with the fish.
Grow bed is 4.8m x 0.5 w x 0.35 d.. I was always going to add more beds as the fish got bigger and/or the beds were grown out.

I have attached a pic of one of my dead fish, and m

More pics

My tank has a continuous pump, half the water just shoots back in to help airate. Some of the fish have been dying with their mouths open, thought maybe need more oxygen, so i have added another pump just to squirt water out and help airate it....
I also meant to mention, my water has never gone clear, not since i had my first lot of silvers (which i killed) back in october 08.
Not that im that fussed about it being clear, just good to be able to see if the fish are acting wierd.

I reckon your pH is too high for your plants , but - is that a galvanised growbed ?

yeah it is galv or zinc......i was going to did all the gravel out and line it with plastic, is galv/ zinc an issue
whats the best way to lower the ph?

I'd line the growbed for sure . someone who knows more than me can tell you whats wrong with galv/zinc

maybe thats whats causing your pH to be so high .
Mine was over 8 for months , then suddenly started dropping & now its been at a stable 7.4 ever since , no matter what I put in there ( which is good )

I'd make the next growbed , line it , then transfer the gravel into the new one , so you can line the original one - if youre gonna build another anyway , why double-handle the gravel

to lower the PH is pool acid OK? Obviously as long as it is very gradual and in small doses...does anyone know of any other ways?

What's the media in your growbeds....??

pH 8.2 wont be doing either your plants or your nitrifying bacteria any good IMO... but will grow algae.... although it doesn't look tooo bad.... you need to try and adjust it...

By the way... how big are the SP's that have died??.. i.e about the size of the one in the pic...

Not unusual for the smaller Perch to die when that first cold snap lowers the tank temp quickly....

And if you went from around 20+... down to 14-16... then it's probably just one of those things...

I lost about 4-6 around mid April when the tank temp plummetted for a few days....

Did your water go "milky"/"cloudy" around the same time??

P.S ... most fish will appear to have open mouths in death... so it's not a good indication of DO problems...

And I don't know how much you're feeding your fish... but you really need another growbed for sure...

My wife lost aquarium fish, gambusia, overnight using rainwater from a zincalume roof. If all other explanations fail, then this maybe the case. Zinc poisoning from your zincalume/galvanised grow bed.

the SP mainly all the ones i have lost were small... ie. 50mm or so, the one in the pic was 100mm , one of my bigger ones, so i have been s**ting myself as i thought perhaps it was just they were a little weak. I then lose a bigger one and start to question everything.

I have warmed the water up, trying to get them back to their ideal conditions to stop any stress... i will lower the PH over the next week with some acid and see how i go.
Any input on the flood drain time or is this really irrelevant?

i meant to say the media is just pea gravel about 8mm

DO NOT change ph FAST ..... that will kill the fish.

Time now is perfect to try an reason WHY your PH is so high and why your temp is unsuitable for your fish.
Radical changes will only do more harm
.

I did a 1/3 water change yesterday... I will take some more readings today....
The thing with my PH is it has always been in the 8's since i first set the system up....
the guy i got the fish from (gidge fish farm) said ph in the 8's is fine, and its more ph swing which stresses the fish, but i never thought about the high PH affecting the plant growth. I have read since that the higher PH means some minerals are insoluble so the plants are unable to absorb them into their roots.... Makes sense now.....

the tank is lined with drinking water grade liner from Rhino tanks, would the gravel be raising the PH?
I have a friend who runs exactly the same set up (ie. with gravel and galv beds etc as we bought it at the same time) and his PH sits at about 7. His only difference is his tank isn't lined its a cbond aquaplate tank.

I would not lower your pH until after you get the grow bed lined! The more acid the water the quicker zinc and copper become toxic. (Even people can become sick from zinc overdose if they drink apple cider that was processed in galvanized tubs.)

pH. What kind of rock is that pea gravel? If it is limestone, that will be what is causing your 8+ pH. Adding acid will not bring down your pH effectively if your media is buffering it up that high, you will only succeed in dissolving some of your media.

Very good points TCL.... but I think the pH could, and should be adjusted back slightly for the sake of the bacteria.... say to 7.8 minimum...

But yep... preferably, empty the growbed and line it first... or bring another online and then repair this one...

wow.. that's a really interesting difference..
how far does he live from you? i mean is he at an higher or lower altitude from you or different parts of the Hills?
I know most of the hills, my mum lives in chidlow so I visit gidge and mundaring and midland a lot. I also visit kalamunda and the wine valley. I'm asking because I'm curious whether the altitude will effect the ph.
Coz i know it draws a huge difference in day and night temperatures depending on which part of the hills you are.
Also there's a lot of mixed rock types in there... granite, shale, bits of limestone managed to wash over some of that, there's quartz mixed in as well as pea gravel all over the place. So yeh very interested...