Another Sump / Flow question
 

Just finished up replumbing my 90 gallon tank. Turned the Durso into a herbie.
I have an 1 1/2" drain with a gate valve and a 1" return. Pump is a Waveline DC5000 putting out 1320 GPH at the pump. estimated 850 GPH at 4' of head height with a couple of elbows. I am running the pump wide open and the gate valve on the drain is almost closed to keep the water in the over flow at the height I want. I have tried this with a Quiet One 4000 with the same results.
I know the suggested flow rate is 5-7 times the total water volume but wouldn't it be better to have more than that if possible.
How much flow would one get through a wide open 1 1/2" drain ??

I've read that flow rate through a sump, for proper skimming efficiency, is 6.1 times per hour
This would, of course, be comprised of your total system volume
1-1/2" drain has a potential of about 1350gph

Edit - apparently the calculator I use is way off for the drain

I have an 1-1/2 drain and 2 1600+gph pumps and my gate is almost closed as well. At full siphon it will handle wayyy more than that. The only problem Ive come across is setting the gate with that much flow it becomes very sensitive.

Greg is right about sump turn over. Although I don't see the down side of more flow.

With my limited experience, the only downside I see with more flow is faster sock pluggage ( good thing ) and less truly skimmed water re-entering the DT ( not so good )
I'd think that introducing un-skimmed water back to the DT is kinda counter-productive where surface water is concerned

I don't know why it bugs me so much LOL even considering reducing drain pipe diameter just so I can open up valve more :twised::twised::confused:

what size is your back up drain?

One thing to consider when going with high flow through the sump is that your return pump is going 24/7 so the higher the flow, usually the more electricity you'll use. Just discussed online with another reefer how his hydro bill went up $100 due to his tank and he had a Mag18 on a ~45g display which uses almost three times the electricity of the much smaller return pump on my 165g display (90g wide sump). Our hydro bill went up 7% this past month and so having a powerhog of a return pump going 24/7 is a real concern for me.

Just a thought.

Electricity is one thing to consider when choosing a return pump. Here, it costs 11.35 cents per kWh. So for every 100 watts run 24/7 it costs about $100 per year for me. I have a hard time believing a 45 gallon tank would cost $100 per month though. If all devices on my tank (powerheads, skimmer, heater, lights, and pumps) ran 24/7 on my 90 gallon reef it wouldn't cost me $100/month.

Here is a nifty calculator:
http://www.citytrf.net/costs_calculator.htm

Another drawback to more flow through the sump is that the higher flow usually drags microbubbles with it which get chopped up even further in your return pump and blown into your tank. This affects the visual clarity of your tank, and irritates from corals.

1" Emergency drain, could swap them, I suppose. Probably fine the way it is.

HMMMMMM, yeah . Not really sure if I want me power bill to go much higher. The DC pump uses 40W at full speed.