Backyard Aquaponics
A place to discuss aquaponics

i have a price on a 9000 lt poly tank @$1895 delivered. The lid is removeable however th sides are corrugated. Will corrugations make the tank harder to keep clean? Is it preferable to buy say two 5000 lt tanks rather than one 10 000 lt tank. I have plenty of room. Im thinking grow out size might be affected by tank volume.

If it was me and I'm guessing its for fish tanks. I'd go the 2 x 5000ltr tanks without removable tops. Then cut 30 to 40cm off the tops and end up with 2 X ft and 2 X large gb's.

Hi Bluefin

I can't see any issues with keeping a corrugated tank clean. In any tank the amount of light that enters determines how much algae you get, so keep that down and all should be sweet. A stiff broom will take care of any cleaning regardless.

As far as grow out a 5000 litre tank should be ample. How many fish and what type were you planning on having?

You mention corrugated, that makes me think galvanized tank. Please make sure any such tank you wish to use with fish is aqualined or you could have zinc problems with your fish.

As to tank cleaning. My generally inclination is once you get the system built and cleaning the first time, never clean the sides of the tank, that bio-slime is good stuff. The only cleaning I really worry about is getting the blobs and pockets of solids out of the bottom of the fish tank as they can get anaerobic and be a bad thing.

tank is poly not metal. i already have 150 silvers in a 2500lt tank, i just intend to increase the size of my system. The existing tank is a former septic tank on an adjoing block of land. It is 2 mts deep, i was going to change to a chift pist system and use it as my sump. I have noticed that because the inside of the tank surface is quite rough that a large amount of algie/biota attaches to it. I have a lid with 70% shadecloth on it so the tank is not exposed to full sun. The water itself contains a lot of very small particles in suspension, i suspect it is fish poop, algie etc. It does not seem to be extracted from the water by running through the gravel growbeds. I suspect it may be caused by overcrowding, as the fish are at 200mm to 250mm in length and puttting more demand on the system. Duff i like your idea of cutting the top off the tank. Will that affect the stuctural integrity of the tank, causing it to go out of round etc? The tank guy told me the removeable lid tanks are cheaper as they can be stacked for transport. The lidded tank could be reassigned to a rainwater tank at a later date if need be.The latest bunnings catalogue has a 5000 lt for $980.

I think the rough surfaces would be an asset in that more surface for bio-slime to grow and catch more of those tiny particles. I too have noticed that there is a fine material that does make it through the grow beds but luckily that stuff doesn't seem to bother pumps much the way the fresher fish poo clogs them.

I have decided to go with the 9000 lt tank. It is 2900 in diameter and 1500 high. The only problem is my partners eye height is 1500, oh well i will have to make sue a viewing platform to stand on or she might have to wear heels.

Plastic tank sides are thinner at the top and get thicker towards the base. If your going for the bigger one you may be able to slope the ground that it sits on. Dig a funnel shape tapering towards the centre. Then when the tanks fills the bottom will have a cone shape. The solids will move to the centre and you can have a bottom fed over flow to remove them. Not sure what angle to use. My large swirl filter has wedges to adjust the base.

Ever thought of diging it in 500

That'll help stabilise the temperature too

+1 on the tank being burried. The sump im using has maintained an almost constant water temp of 22 deg c from oct to apr. However the position where im going to locate the new tank is ontop of pavers on concrete so ill have to hire a back hoe. Thanks for the advice folks this is the first time i have ever kept fish and the fact i have had only one fatality is amazing.