<a href=showthread.php?s=&postid=6549466#post6549466 target=_blank>Originally posted</a> by ninjafish
Ryan,
Thanks for your comments about my tanks, I'm glad that you stopped by.
To answer your question about the auto topoff amount, when I first set up the ato on my 2gal cube I paid attention to how much water I was adding to the tank by hand (about 350ml). I set the pump output to match this and then watched it for a week or so and slowed it down if the water level rose over a few days and sped it up if it looked like the level was rising.
When I went to the 7.5 gal cube, I just multiplied my dosing rate by 3.5 and then watched it again to fine tune it. I have now found the magic evaporation rate of the tank and the water level only varies by a quarter of an inch up or down if I leave it for as long as two weeks.
Usually though I do a water change when I come in to work at the start of each week. I change 3gals of water at a time which is about 30%. This is more water and more frequent than I really need, but I do not dose any other suppliments and want to ensure that my stoney corals are getting enough calcium from frequent/large water changes. Also, the mantis puts a surprising amount of load on the system and I notice that if I go too long between water changes, the diatom algae builds up on the glass a lot faster.
As for my return flow, the water shoots directly up to the surface; in fact, I have carefully positioned my rockwork so that it doesn't get in the way. I have found that not only does it give me healthy surface agitation, but the current hitting the surface of the water causes it to umbrella down on every side and provides the most even circulation without dead spots.
I hope this helps. More pictures are on the way I promise.
Cheers,
Chad