TURNOVER VERSUS FLOW

[Scuba Steve]

Hello

I am still confused regarding turnover etc. Some people seem to refer to turnover as 2 different things. Given that my system is 700 ltrs could I ask the following?

1. How many LPH should my main return pump in my sump be rated at to be adequate?

2. How many powerheads do I need in my display tank and what LPH would be adequate for each?

3. Should these pumps be arranged to maximise flow over the drop off wall or at my rock to assist in keeping it free of debris?

I have read that turnover should be between 10 - 20 times and initially i thought this referred to the return pump in the sump but now I'm confused.

Regards

Steve[/u][/b]

 

[MT79]

. How many LPH should my main return pump in my sump be rated at to be adequate?

It should be able to move about 10x the amount of the display per hour. The rest of the system turnover comes from power heads in the tank or closed loop set ups.

How many powerheads do I need in my display tank and what LPH would be adequate for each?

That depends on a few things like how much rock you have as that will block flow, tank depth, you want good flow throughout the tank, and also as corals grow and get larger they block flow. You may need to increase flow in the future, a year or two down the road. I think a good way to describe adequate flow is the coral polyps should sway as if blowing in a gentle breeze. You want chaotic, turbulent flow as well. Bouncing power head streams off each other and the glass front/sides of the tank help create turbulence. Wavemakers are a good investment IMO. I use a cheap SCWD "wavemaker" on the return line from my sump.

Should these pumps be arranged to maximise flow over the drop off wall or at my rock to assist in keeping it free of debris?

You want to keep detritus in suspension so it can be removed by skimming, etc. You want good surface agitation to allow for good gas/CO2 exchange to maintain high PH and to prevent DOC's from accumulating at the surface. That will cause a film to develope and block light, is unsightly, and may inhibit gas exchange. Also you want water to be pushed through your LR to aid in filtration. And as mentioned above, corals need flow to deliver food and remove waste. It's basically how they respire. Some corals, such as SPS, require more water flow than others.

HTH
Edit- I'm not sure the coral info will help, forgot this was the FOWLR forum, oops!

 

[melosu58]

It should be able to move about 10x the amount of the display per hour.

This would be my answer also.