Backyard Aquaponics
A place to discuss aquaponics

Hey all

i have a small system thats about 2 months old

Its been a rocky ride and its finally stabilised (massively overstocked at first)

Ive got about 20 - 30 Rainbow trout fingerlings in 1000l

As far as i can work out my levels are still to high, but i havent had a fish death for weeks

Also the fish arent showing any signs of stress

Ive got

Temp 18C

Ph 6.4

ammonia 2ppm

Nitrite 1ppm

nitrate 10ppm

Ive salted the water to 1 ppt also


so what should i be aiming for with my trout?

and are these levels still dangerous?

Thanx!

What is the volume of filtration i.e. GBs?

As Bunson asked, what volume of growbeds do you have as part of the system?

At 20-30 fish you're still almost certainly overstocked - the system just looks stable as the fish are only small at this point. The larger the fish get, the more waste they produce and room they need.

Aim for, at least 750l of GB volume/filtration, maybe more with only a 2 month old system

Ok what chemical levels in ppm are trout ok in

You want your amm and nitri to be a zero, you could get away with slight amm but zero is your aim.

charlie your a gentleman thankyou

i have about 300L of filtration

50 of these are a kind of homemade canister filter so i think they will offer better filtration than a normal growbed

i know im overstocked but i will monitor levels and do what i can to make it work, water changes remove fish etc

right now the fish are so small its still ok

and to promote bacteria growth i want the watses in there so long as thier non lethal

i also rent ... so more system expansion just isn't an option for me

What's the filter media in the 50L canister?

Course smooth river pebbles then scoria reducing in size toward the top then at the top there's clay noodle and some plastic mesh

The canister filter you have made performs one of the filtration techniques required in AP systems, the removal of solids. If you regularly clean the filter (daily or better) you will remove these before they can start to break down (mineralise) and generate waste products of their own; this is good; if you're not cleaning regularly enough, the wastes collected in the canister will just add to the ammonia problems.

Regardless of the cleaning regime, the problem remains though, you have insufficient surface area of media for sufficient colonies of bacteria to perform their bio-filtration activities. Other than reducing the loading on the filtration by reducing the number of fish (get any friends/family to whom you can gift the excess fish?) you need to increase the bio-filtration capacity; either add more growbeds, or specific purpose bio-filters.



In terms of capacity vs volume, moving bed (fluidised) filters using Kaldnes K1, bio-balls or other similar high surface area media are excellent (but can be pricey, look on eBay for the media as you can find it cheaper!) The next option is to use something homemade, like plastic bottle tops, drinking straws, PVC pipe rings etc. Whichever media you are using, add these loosely packed to a large container with an aerator. The water going into the filter should be pre-filtered but as the water flows through here these filters are not prone to clogging and are in fact self cleaning.

You can make static filters by taking a container and filling with scrunched up shadecloth, fishing nets, flyscreen mesh etc; anything which has a large surface area. This water must be pre-filtered else the material will become clogged and you'd just end up with another large solids filter instead of a bio-filter.

For a good introduction/summary of what growbeds do in terms of filtration :
http://www.backyardaquaponics.com/Travis/Backyard%20Aquaponics%20-%20media%20bed%20model.pdf
http://www.aquaponic.com.au/Aquaponic%20media%20bed%20sizing%20model%20explanation%20-%20metric%20Ver%202.0.pdf

To see a discussion on how others have computed how much filtration:
http://www.backyardaquaponics.com/forum/viewtopic.php?f=1&t=11009

A discussion on bio-balls and DuffLight's simple filter video;
http://www.backyardaquaponics.com/forum/viewtopic.php?f=5&t=8505

Some plans/designs/ideas/inspiration:
http://www.backyardaquaponics.com/forum/viewtopic.php?f=1&t=5987

A video of the manufacture of a simple bio-filter:
(No, I'm not interested in arguments about galvanised screws or water levels etc... please just use the video for inspiration)



What K1 media looks like in a moving bed filter:



Whatever you decide to do, you'll need to do it soon. Everyday the fish grow, they will be increasing the load on the system.



HTH

Scott

Bunson, thanks a lot for the info collection. Very important and explainable