Backyard Aquaponics
A place to discuss aquaponics

Hydro Tech - thanks for the tip re polycarbonat. Is polycarbonat food safe?

Regarding windows and aquasonic, they actually sell a window for installation on their tanks. Not inclined to buy one as it would have to be much cheaper to just source the materials myself and whack one in. Can't remember how much they charge for just the window though - may check it out sometime.

Of course - I could always just continue to watch the fish from the top of the tank like I do now

I vaguely remember polycarbonate is used in the medical industry, and at the local camping store, i can buy Lexan (a trade name for polycarbonate) drinking bottles, and breakproof polycarbnate cups.

They make tuppaware type stuff with polycarbonate, so it must be food grade.

I think Carribean Grower also was working with NFT.

alchemist, so are you removing all of your solid wastes?

Jims AP tommies are going great in the NFT channels........

there are quote a few members doing nft with a gravel bed before the channels as a biofilter / solids trap.

Thanks , interesting variation. In my case only the coarse solids are removed dependent on the pore size of the cloth used in the screen filter.

Heres last years nft photos solids are filtered out first

And Jim has quite successfully converted his hydroponics system over to AP... photo from last weekends Vic meet

http://backyardaquaponics.com/forum/vie ... 137#103137

Same proviso.... solids must be filtered first....

i'm going to highlight the distinction between filtering solids and removing them.

Keep us updated alc. i'd be interested to see if you have any trouble with fruiting plants.

Will let you know as trials progress. Our focus is on culinary herbs and lettuces which, with its lower nutrient level, I'm told this type of system is most suited to (I'm sure you know this :-) ) but we are having a look at fruiting plants for interest.
Does the level of suspended solids have a significant effect on nutrient availability?.

To many solids will clog the rootball and cause root rot

i guess its a correlation that has been seen enough and is spoken as fact here.

From the 60's and 70's books and documents i have read aquaponics was a mere foot note in hydroponics listed as "only useful for leafy greens" all of these systems remove solids to waste

in contrast we keep all solids trapped in the system and allow them to mineralize. we also have no problem with fruiting plants from tomatoes to peppers to pumpkins. sometimes they go better after a number of months.

We all know of the high levels of nitrogen available in AP due to the ammonia conversion to nitrate and that vegative growth relies on primarily nitrogen.


The conclusion that many of us have drawn from this is that there must be significant phosphorous and potassium in the solid wastes that becomes available to the plants from within the gravel bed.

I stress that it is a conclusion drawn from the above observations.

it would be very interesting to have the water analysed from two identical sized systems with the same number of fish and plants (a fruiting variety) and the same feed rate for the fish.

this would give both a visual confirmation and a chemical comparison so that this theory may be set in stone

Al, I have been very surprised with the fruiting aspect of my system.
It is a VERY young system, having been operational for a little over 2 months.
Of the 2000lt of gb space, nearly half is devoted to tomatoes, pumpkin, eggplant and zuchs.
We have picked several kilos of baby pumpkin already, pick zuchs daily and have a mountain of tommies on the vine.
The only thing I have added to the system is iron chelate ( 2 dissolved teasp per month, and a quarter of a banana per gb for potassium/flowering/fruit set.) My fish food is currently the growbest barra pellets.
The flowering aspect and fruit set has really surprised me. Fish pellets have a fairly high percentage of potash and I wonder if this also has something to do with it. Dunno.

Thanks for the clarification. I mentioned earlier in the thread that I built a seedhouse for my wife prior to the aquaponics polyhouse. It has slatted tables down each side which are well occupied with her propogation and plant growing activities but there is still an unused 11m x 1.6m section in the middle which was originally intended for run-to-waste hydroponic tomatoes. I subsequently realised that run-to-waste wasn't the ecological way to go but have thought about the space for future flood and drain aquaponics. Could be the way to go for the fruiting plant side should this not suit the raft set-up as I (and thee) suspect.
Since members have shown some interest in greenhouses,I will attach a pic of the seedhouse in another message. As I said before it was a design I got off the net. It came from an outfit in Utah called "Feed the World" I recall.