GrahamC

90L should be enough for the 6 juvenile angelfish though ...

Know very little about marine except what I have gleaned from surfing but my understanding is that marine tanks have their bacterial colonies on live rock.

It's a tank maid, and currently it's just under the water line with the output at 5 cm below that ...

I think it is water pressure on the pump itself ...so that there is greater resistance to outflow. With this the water velocity drops, and so the negative pressure at the venturi port drops.

I guess we can extrapolate to the tubes in question and say that 1% of whatever might reach 3m but won't have any biological signficance. Lower frequencies of UVB exhibit rapid fall off in the first 5 mm of water.

I only scanned this paper briefly http://www.int-res.com/articles/meps/144/m144p109.pdf but I found a few sentences that say 1% of solar UVB is found at 3 - 9 m depth depending on location.

I want to be able to recirculate the air at the top of a bottomless tank so external air pumps will not work as they will introduce air into the system dropping the water level. Based on my experience so far, I suspect the pump itself will need to be outside the water column to reduce the water pressure.

Toxic to fish; 50 ppm leads to 50% mortality in 72 hours. Seems to be a CNS depressant, and likely causes some necrosis to both piscine liver and muscle cells. http://www.sciencedirect.com/science/article/pii/S0147651302922128

Have wrigglers in Wgton. I put out a plastic box earlier last year for the chooks to get fresh water ... and now it has leaves and other stuff in it including duckweed with the long root systems ...maybe 4cm. Have some pond snails which hitched a ride with the duckweed. Interestingly I don't see any algae on the sides of the box. I noticed some wrigglers there end of last year and have been harvesting a few each day for the WCMM, and now for the very choosy angelfish that refuse flake I see that the recommended method is to pour from one bucket to another thru a brine net but that would catch all the leaves, snails and duckweed, so I use a turkey baster to suck them out .... very time consuming!

I bought about $80 worth of various bits in November ( added xtras to a TM auction ) and the stuff arrived promptly.

That won't work if I am looking to buy a filter for this purpose

So, if that is correct, how does one calculate how deep one can immerse a filter and still have the venturi still work? I presume that the variables are water depth, rated litres per hour flow, and diameter of the outflow, diameter and length of the airline tubing ....

I have a venturi port on my submersed filter that allows air to be mixed in with the filter output. But I noticed that it stops working if I submerse the filter too much below the water line. Since the air line hose length is not changing, and atmospheric pressure is constant, then it must be the increased water pressure that is limiting the water flow and reducing the negative pressure at the venturi port?

Here's a description of how they might be used in a marine tank http://www.alltropicalfish.com/content/view/109/101/

Yes, a gravel tidy is a fine mesh used to separate substrates and to also stop fish from removing the gravel above an undergravel filter. So, you would have UGF - gravel - mesh - gravel or sand ....

Do people use gravel tidies, and if so where to get or how to make one?

Craft canvas is only $5 a sheet from spotlight, and can be re-used indefinitely. You could stuff some filter wool at the end of the cylinder formed by wrapping the craft canvas around the filter intake if you wished to create a smorgasbord.

Carbon is cheap and should clear the toxins. Also check the surface of the water to see if there is an oil film on top. You could keep on with the water changes but if there is an oil or toxin adhering to their gills etc, then continuous cleansing with carbon as well can only help.

Have you put a filter with activated charcoal in it to clear out any residual toxins/oils?

Need to watch the video I think I missed a step in my description. A poster comments:

Can go to 30 deg C which is the top of the optimal range. Resources suggest doing a partial water change if nitrites off chart. Don't you have any live filter material you can chuck into the tank to speed this all up?

I might just do that :thup: There's no shops in Wgton that I know of that have salt water stock which seems a shame since we are surrounded by the stuff!

You can put a heater in if you haven't already ... as it is a biological process you can speed it up that way.

I used a bucket and hand to swirl the silica sand repeatedly changing the water until it was clear. There is a very smart way to clean sand posted as a video on youtube. Basically you put the sand in a bottle, and fill it with water. You then put it into the tank which is filled with water, and near the bottom, you then invert your bottle. As the sand comes out, it is replaced by water coming in and this incoming water collects the debris and dust which is lighter than the sand. You then remove the bottle with the dirty water. Didn't work for me as silica sand is too fine and won't come out of an inverted bottle like that

Maybe you could put some fry in there, or, turn it into a water cooler for your CPU? Must be the season for this .. someone forwarded an offer from World of Water for a 55% discount on an aquarium starter kit.