Backyard Aquaponics
A place to discuss aquaponics

No, not with Nitrite.

Fast growers such as Trout, Barra, Murray Cod etc need 25L of wet gravel per fish to get them safely to plate size. Silvers you can get away with 20L per fish.

I haven't set up a cistern but intend to ASAP, how can I test current roofing for things that will be harmful to my future system and what should I consider doing to filter those things out if need be?

you can only really get the water tested in a lab for key metals - not sure how much it costs in US, but not that cheap here in Aust ($50-$100 per sample).

some members have reported issues. If in doubt try and harvest from poly carbonate sheeting or the like.

not sure if you can filter - zinc, copper and lead are the common ones.

Thanks to all those who posted advice, I have changed out app 35-40% of my water over two days, still running the pump full time and feeding the trout minimally, I've put more plants in (was doing this anyway). My ph is 7.2, amm is 2.0, nitrites 0.50 and nitrates are just on the scale at 2.5 ppm. These levels have been the same two days running. The fish appear happy enough, not flashing or moving erratically, I guess I just continue watching levels and wait for cycling to complete, change water again if amm and nitrates start to increase again or do I keep dumping water?

basically got to focus on keeping the ammonia down until it sits steadily at <0.5ppm (ideally 0-0.25ppm in the tests).
if it starts to rise then keep doing water changes - there will always be ammonia present so it wont affect your bacteria (which is in the media). Also 0-0.25 for nitrites.

Nitrates are fine as long as they are <80ppm and ideally (ultimately) less than 40ppm.

If you struggle to keep the ammonia in check then you may have to reduce number fish or increase media volume (add an extra grow bed or use a bio-filter of some description).

pH at 7.2 is a good place to be.

[edit] don't forget to keep your salt up as water changes will remove salt. You may have to balance your veg with something that can cope with salt, otherwise it wont use nutrients.

and yes to pump - with nitrites and ammonia you need to keep your oxygen up, and it helps to circulate water within FT.

Ok when you say balance veg with something do you mean choose other veg that can handle salt?. I am assuming these swings in amm and nitrites are just because my system is not yet cycled but once the bacteria are doing their thing the system will tend to balance itself to where it's happy (providing I don't make a major change like yanking all my plants or fish out in a short space of time)?

>> Ok when you say balance veg with something do you mean choose other veg that can handle salt?.

yep. Salt cuts down on what will grow - you can just choose something temporary for couple months till things settle down. Then lower salt and be ready for mid-late spring.

I don't salt very much/at all but one of the guys will know what is better to use.

Hi just an update of my system levels, ph 7.4, amm 0.25, nitrite 1.5-2, nitrate 5. I'm probably being impatient but the nitrate hasn't budged off 5 for the last three days even though my nitrite levels have been high and temperatures milder over the last week. I've salted to 1ppt and am feeding app 1/2 tbsp every two days, pump still running constantly. I changed out about 30-40% of the water two days ago which seems to have kept the nitrite from rising much. Should I keep changing water if nitrite stays where it is? I've also noticed a few of the plants leaves are yellowing is this resolved with chelated iron and if so how much do I add.
Thanks in advance for any assistance

don't add anything to your water while this is sorting itself out.
if you like use a spray bottle and give the plants a bit of a foliar feed - chelated iron from Bunnings will be fine.
also a bit of seasol.

your water temps are probably cool so it may take time to get the 2nd phase bacteria going.
do water changes as you are to keep the nitrites down.
also the plants wont use as much while it is cooler.

still got to just ride it out... things probably happening a bit slower, but its only been a few days.
could take a week or little bit more.

keep in mind that your ammonia is not static because the fish are producing more of it.
so 0.25 is good. And if nitrites/once are holding steady then you know you have the 2nd stage bacteria active.

Happy days Darren, I'm back to pumping 15 on 45minutes off and feeding fish app 1/2 tbsp per day.
Ph 7.6, Ammo 0.25, nitrites 0-0.25, nitrates 40ppm and rising. Thanks for the advice from everyone I think it's cycled.

Good to hear. Sounds like you are over the hurdle. pH 7.6 is good place to be in a young system as it will/may still come down a bit. Anything 6.5 to 7.8 is good IMO anyway and even 7.8-8.0 is OK for many systems.

FYI I tend to run my system on 50% (30mins-30mins etc). That way you keep water moving through the beds and thus get more filtering and aeration. Keep in mind you also need to make sure you are circulating enough fish tank volume during your pumping period (ie. at least one full volume as a rule). So extending to say 30-30 improves the turnover and still gives you 50% saving. In my case for my side of house setups I run four pumps on 2 power feeds, so 30-30 effectively means I am running 2 pumps 24/7 as I have each pair on opposed times.

If you pumps are the main source of aeration then net pumping time is important for Dissolved Oxygen (DO), particularly if you want to run DWC's, or PVC pipe systems etc.

As you stock at higher levels you need more and more circulation.