Backyard Aquaponics
A place to discuss aquaponics

How long is a piece of string?

maybe 1 airstone per 1000 liters of water?

The fish farms that I have seen usually run about that - but they are putting a fair bit of air through that one stone.

I have a 20w air pump running through weeper hose in my 8000 liter tank, water pumps have been off for 12 hours at a time before, with a lot of trout in the system. No problems.

When I spoke with a guy at Aquatic Eco Systems he gave me a rule of thumb about air (sorry, I'm in the USA so the numbers are in our annoying units I know.) He said 1 Cubic foot per minute of air per 400 gallons of water would keep the fish alive for a time even if my pumps were dead. So you need an air pump that can provide the appropriate volume of air at usually 2 psi. Each 28" of water depth requires 1 psi (pound per square inch) of pressure to push the air down that deep and generally you need another 1 psi to push the air through an air stone. Get an air stone that is big enough to handle the amount of air you wish to push through it and use the largest appropriate tubing.

All that said, you do have some water flow happening and probably only need a little extra aeration.

I've got a problem with plant growth currently, or lack thereof.

It started with my cucumber having what I thought was a potassium deficiency. After some doses of cream of tartar, the problem seemed to get worse over the space of 2 weeks, until today where most of the leaves have died/ar dying. I've got one cue off it which was fine, and another 2 which don't seem to be increasing in size. I'm waiting another week or so before I make the final assessment.

My cos lettuce never reached full height, and after some weeks have remained at what I call 'baby cos' proportions. My iceberg lettuce suffered the same issue until I picked them last weekend, at what can only be described as undersized (about the size of a softball).

The tomatoes I planted about 3 weeks ago are growing in height, but I noticed today all the leaves on a couple of branches dying off.

My celery planted 3 weeks ago don't seem to have grown at all, and even the new shoots appearing have stayed the same size.

I've planted some more cucumbers, mizuna, eggplant, zuchini and some herbs on the weekend, and noticed today some spots appearing on some of the leaves.

I'll try and post some photos tomorrow, to let you see what I mean.

I did some tests today, and PH was 7.8, ammonia and nitrite were nil, and nitrate about 5. Apart from the few teaspoons of tartar a couple of weeks ago, I've only added seasol (about 50ml per week).

Any guesses at what could be causing these problems.

BTW, the fish seem healthy and are eating fine.

There may not be enough Nitrate, how much water + fish do you have again?

Is it seasol concentrate? 50ml is not much.

I thought nitrate might be the problem. I have a 500L FT and a 500L ST, with 20 SP fingerlings (about 5cm to about 9cm).

I recently installed the ST - maybe there's too much water for the amount of fish?

Let me correct that - given there are nitrates present, I assume the plants have nitrates to feed on. Isn't it correct that the amount of nitrate doesn't matter, as long as it's above 0 and stable?

How much seasol concentrate would you be adding to my setup (500L FT, 500L ST, 600L GBs) per week? Or should I just be adding more as soon as the water clears?

Also, how much is too much, and what are the dangers of adding too much? I think I remember your post OBO about adding so much the water went very dark, with no adverse reactions?

only 20 very small fish in 1000l = no growth. You have nitrates, but not really enough fish food going into the system to add the rest of the nutrients.

My 1000 litre (400 litre GB) system gets a big handful of urea every week, and probably 1 cup of seasol every month. I am running it fishless as a bit of an experiment. Sorta natural hydroponics.

I'd put 1 cup of seasol concentrate in, growth should take off. I'd say your missing some element that the plants requires, seasol will most likely add it.

My big system only gets seasol whenever I notice that fruit is not forming, or growth is slow. 8kl gets 2 litres of seasol over two days. Usually once every 2 or 3 months, depending on season. Never had a nitrate reading on this system.

600 litres of growbeds beds should be able to support over 50 big fish once cycled, so you are very lightly stocked. Your limiting factor is the fish tank size, but if there was say 40 in the FT and 10 or so in the sump it would work pretty well.

Just add a cup of seasol concentrate, wait a fortnight - it will take off

It's a personal choice...
I don't use Seasol, and other don't use it.
Then again others use other stuff I don't use.
For me just fish, water, and fish food.
All in good time!

*sigh*

Would you rather that people who have very lightly stocked systems and have low plant growth, simply give up AP?

not at all...OB
I would be more interested if the P word was used a little more.
Considering the fish have only been in the system a month.

All I was saying is that I and others are perhaps more willing to
wait for the 'natural' cycling to take place, if there is such a thing.
Natural that is!

I am down to only 9 big trout and about 15 marron and still I have phenominal growth.
with a 3000ft & 1000l sump and 4x500l growbeds.

I have a coupla mates that are interested in my system, they visit from time to time.
both keen gardeners and each time they have been here they have jaw dropping
looks on their heads.
I am wondering if I am just lucky but then I see the systems at the shop,
no I am not lucky(other than to find BYAP) thats how they all go!

Only MHO

Kick back and watch I say and do!

Thanks guys - I understand both opinions. Luckily C1, you don't need to use seasol. I cycled my system for about 2-3 weeks before adding the fish, and for a week or 2 after adding the fish all was going well. I'm not sure if it was adding the sump and extra GBs that caused by issues, or adding the potassium, but I think the plants hard started stalling before then anyway.

However, I don't think it could hurt, and hopefully very much help, adding some seasol to address any nutrient deficiencies I might have. It seems plent y of others use natural additives for this problem, including seasol, worm tea, weed tea, etc. I'd prefer not to have to add anything, but am willing to accept I may need to always use additives to keep the system happy.

Anyway, I added about half a cup (roughly) of seasol this morning, and will kepp you posted on any developments.

Thanks again - your advice is both helpful and encouraging. I'm definitely still a believer in the cause

Is yours all Hydroton C1, whats your media Ry?

Maybe your media is similar to mine.....plain hydroton seems to grow better than gravel based systems....

My original 400L is "salt and pepper" gravel. The additional 200L is hydraton.

Yes OB it is
aqua clay to be correct.

hmmm, something to watch...