Backyard Aquaponics
A place to discuss aquaponics

I wouldnt necessarily say that all calrifiers and settling tanks need to be cleaned daily or aerated. I clean mine once every 2-6 weeks, takes me about 30 minutes and im back in buisness. Takes about 20 gal of water in a 1000gal syatem. It really comes down to filtration design. Take the UVI system for example....If they piped the wasteline directly to their sludge pond, they would just need to open the valve for a minute, then shut it. Done deal. The auto top off would bring water levels back to normal. They could also come up with a quicker way to wash the netting material and cut down on time. Maybe have 2 different nets, take one out, drain the tank through a bag filter and pump the water back into the tank, then put the spare net right back in. Then take the dirty net, hang it from something and hit it with a pressure washer. Leave it there until the next round.

It is a lot easier to design a system for ease of use up front then it is to go back through and rework everything after the fact.

HI,
Ok to clarify water capacity of the filter,as an example pump output is 2000ltr per hour,filter capacity with no medium is 500ltr,this gives us
500/2000=0.25 or 15mins,
Now fill the filter with gravel now water capacity is reduced to maybe 200ltr or less,so
200/2000=.1 or 5miins.
Now fill the filter with an open medium like matting abd your water capacity will only reduce to 450ltr,
450/20000=0.225 or roughly 15 mins.
These calculations are based on the pump output giving you your turnover of your pond at approx 8 times every 24hrs.
Retention time of 15 mins is said to be the bench mark figure.
All of this is variable there being no substitute for a good test kit to show you exactly whats going on.

Hi,
On the subject of cleaning,surely if you use air in a settlement tank it will no longer be a settlement tank due to the extra movement from the air and leaving to long between cleaning allows dissoloved organic compounds back into the water increasing the work the filter has to do,if you have high stocking to growbed ratio it could give you a problem,you could see ammonia building, up to cleaning time.If everything is balanced plant growth will increase as more nutrients becomes available.Regular water testing will show whats going on.

Hmm....tempting to have a settling tank and dump a few gallons every few days into a bucket to water citrus or other heavy feeders.

I have found that after about two days the solids start to form floating rafts as they decay and form gasses. The outflow should be placed in the middle of the water column rather than low or high to suck the least solid material.

Hi,
An experiment i was growing to try on my settlement.Mine is an oblong concrete block tank 500 galls split into one third two thirds the small weirs into the large,now in the large tank i want to round out the corners and then instead of weiring the water install a 4inch pipe feeding in from one side so as to try to make the water spin in the tank thus pushing the solids to the middle,hopefully making regular dumping quicker,Basically a simple vortex but not as efficient as a vortex pre filter

if using the 1 pound of fish per sq foot of GB, how many 3" net pots growing romaine lettuce would a pound of fish support?
any ideas of plant numbers to the pound?

It is more a function of feed weight per sq ft/# of plants. Feed fish 1% body weight to maintain or 3% body weight per day for grow out. This varies from species to species and with the size of fish but thats a pretty typical ratio you will see in many fish farms.

A good number for Romaine in my experience is .42lbs fish/ft^2 plant bed. Plant spacing depends on specific romaine seed but at say a 10" spacing, 25 plants in a 4x4 raft (16^2ft) is 1.56 plants per ft^2.
1.56 plants per ft^2 x .42lbs fish/ft^2 =
0.65lbs of fish fed 3% body weight (0.02lbs feed) daily/ per plant

I was able to grow 500ish fish (125 pounds of fish) in 300 gallons of water; feeding 1% by fish weight. This fish load was able grow 400 square feet of plants (at 8 inches deep). Cutting fish load to 400 fish, it was obvious that some plants began to suffer from lack of nitrates. Just my two cents...

Cool, was that with tilapia? What sort of aeration did you need to have 500 fish surviving in 300 gallons of water, what temperatures for the water? Of course looks like you were not growing them out completely in this tank as you say it was 125 pounds of fish and a 1/5-1/4 pound fish is a bit small for most westerners to really want to bother with.

I have noticed marked differences in systems based on water chemistry and pH. Where the pH is lower the plants are growing far better and the fish are having more trouble keeping up with supplying the nutrients.

it takes 4 or 5 (yellow) perch "buttefly" fillets to make a pound, and it sells for $15.99/lb at the local grocery store..
but in texas they call most sunfish "perch"

generally when you are talking about the weight of fish supporting some amount of grow bed or some amount of system supporting some weight of fish, we are talking the weight of the whole fish not just the fillets.

Not sure if this is counter productive but traditionally ponds and aquariums deal with nitrate problem with water changes.

aquaponic people (aren't very tradtional) deal with nitrates by planting more plants.. no water changes necessary..

.... yep, why throw out all that good plant growing stuff...

I found this discussion quite informative, and at times entertaining

Anyone got a handle on how much bacteria growing area 1 litre of those bio balls has, compared with a litre of gravel, or hydroton?

I saw a clip on youTube of a dude making his own bio balls! Although I don't know how well they would survive with an elastic band? Could we use silicone or something instead of the elastic band to achieve the same end?