Return pump help

[Tphill]

Hello. I'm getting ready to order the overflow box and return pump for my 75g tank. The overflow box I'm going to get is the CPR CS100 rated at 800 gph. The return pumps I'm looking at are the Diablo DC 3500 Variable Speed Water Pump rated at 925 gph and teh Diablo DC 5500 Variable Speed Water Pump rated at 1,450 gph. The return will be 1" flexible tubing and will travel up about 5 feet, over about 2 feet, have a gate valve and a shutoff valve, a T going to the refugium, and a couple of 90 degree elbows. Which one of those pumps would you suggest? Any other suggestions on pump or overflow box? The reason I chose these pumps is the power consumption (30 watts for the 3500, 50 watts for the 5500) and the variable speed motor. Thanks.

 

[LatinKing]

I don't know much of these pumps, since these are new to the market. Personally I prefer external pumps and quite, so If I was purchasing this brand, I would go with the DC5500. Going with more GPH would also be my choice in the event I need for flow. Please let us know your input on these pumps.

 

[Tphill]

Thanks for the reply. I was thinking the larger pump also. I will reply about it once I've had a chance to review it.

 

[AZDesertRat]

You need to know what the GPD is a 5-6 feet of headloss which is where you will be. What does each pump do at that point on the pump curve?

 

[Tphill]

I looked at the curves. The grid lines on the chart are for metric measurments, but approximating gives numbers of about 790 gph @ 5' for the 3500, and 1320 gph @ 5' for the 5500. Those #'s are at full speed with no elbows, valves or anything else. I think the bigger pump will be better because I will not have to run it at full speed, which should allow the pump to last longer.

 

[mcarroll]

First you don't want to push an overflow to it's rated flow - that just invites noise issues and other problems....think of 800 gph as your limit, not your goal.

Second, for a 75 gallon tank 300 gph of return flow should be plenty. Overkill here gains nothing.

Third, you stated that power usage was your #1 criteria for selecting this pump. Unless your tank is overloaded with heat from an "old fashioned" lighting system this is almost surely a waste of money. If your tank is not overloaded with heat (usually LED lighting), then spending money on lower power pumps just makes your heater(s) work harder and makes your tank more dependent on the heater. It achieves no goals you're likely to care about and ultimately saves nothing. Unless you can think of some need for having the ability to electronically change the speed of your return pump (I can't), I'd spend differently. (Seems like a "solution without a problem" to me.)

Last, getting an over-sized return pump is old-fashined. In modern reality, the flow requirement through your sump will not change over time. If you need more flow in the display, it's best to do that with a modern powerhead like a Tunze Stream or Nanostream. (Lots of alternatives.) Spending on controllability for the display flow is more arguably worth the extra money.

I would suggest going with a right-sized pump (slightly over requirement) from a known maker (Mag 7, Quiet One 2200 or 3000, Eheim 1260, etc) and run independent pumps for your skimmer and any reactors you find yourself needing. Submersible pumps are generally more silent (water is an excellent sound insulator) and IME also longer lasting than externals...just avoid bottom-dollar Chinese pumps.

Hope this helps!

-Matt

P.S. I would also select an overflow box that does not use the "open channel" design of the CPR...prone to breaking siphon. Slect one with a standard "J tube" design. (I had bad luck with Eshopps....any other one should be OK.) Something like this would be ideal. Sadly, there's very few Made In USA options left in this category....off the top of my head CPR and Lifereef are it and only one makes a tube design.

 

[Tphill]

mcarroll, thanks for the reply. The reason I chose the 800 gph overflow box was based on researching flow rates. Several threads, on this forum and others, stated around 10x water volume. I believe my system will be around 90 gallons, so 800 gph is close to 10x, and if the overflow isn't 'pushed', just allowed to work, that will be close. Also, I do not believe the Diablo DC pump to be a bottom-dollar Chinese pump.

 

[mcarroll]

10x is overkill for return flow by double.

The exception would be the case where you are also using the return flow as sole source of water movement in the display. This scenario can work but is no longer the best way. It could be regarded as an old-fashioned way to set up a tank. Like getting to work in a Model T Ford…it'll work, it's just far from the best way to do it.

Sorry if I was confusing, but the Diablo is the overkill pump (although cheap compared to other DC pumps), it is not the bottom-dollar Chinese pump I generically referred to.

Excessive sump flow often causes issues with drain and sump noise, can cause micro bubbles in the display, among other possibilities.

There's really no need to exceed 300-350 gph of flow in your sump, and there's certainly no need for a speed controllable return pump…it's a static flow scenario.

Unless you are buying for a tank that is overloaded with heat, a regular pump would be a better choice.

-Matt


Sent Via the R2R Forum APP

 

[Mike J.]

I have a 75 gal. set up with a CPR CS102 overflow. I chose it because it's got 2 bulkheads in case one gets plugged. Well, I absolutely love it. It is completely silent. If I turn off my skimmer the whole tank is completely silent. (I'll be replacing that noisy skimmer.) I have a Mag 7 for the return. The CPR overflow has been running for about nine months without a single issue. We turn off all pumps at least 2 - 3 times a day for feeding. Anyway the 102 is only a few dollars more and IMO the best out there.

 

[Tphill]

Mike J., that CPR CS102 is rated at 1200 gph, and the Mag 7 pump is rated at 700 gph, is that correct?

mcarroll, I already have the CS100 overflow box, have opened and washed it, so it's not returnable. I'll not buy a smaller one, spending more money, so is there a way to limit the flow, and then just get a smaller cheaper pump?

Today is my order day, and I was planning on ordering the pump today.

 

[mcarroll]

Mike J., that CPR CS102 is rated at 1200 gph, and the Mag 7 pump is rated at 700 gph, is that correct?

mcarroll, I already have the CS100 overflow box, have opened and washed it, so it's not returnable. I'll not buy a smaller one, spending more money, so is there a way to limit the flow, and then just get a smaller cheaper pump?

Today is my order day, and I was planning on ordering the pump today.

The overflow will run fine at a lower flow rate.

I think the CPR overflows come with an Aqua Lifter pump to keep the siphon channel clear of air buildup. I wouldn't run that overflow without that pump for extra safety.

-Matt


Sent Via the R2R Forum APP

 

[Tphill]

So a simple inline gate valve would work to slow the flow?
I ordered the deluxe version which included the aqua lifter pump and a lid for the rear box of the overflow. That lid had to be modified to allow the little straw to fit.

I went ahead and ordered the pump, it will be here Saturday. Since it is variable speed, I can turn it down, and once I do add a reactor (or 2) I can use the return pump to power them. My refugium is on the end of the sump, so part of the return from the pump will be diverted to the refugium. I'll also put 2 or 3 more t's/valves in the return line for the possible future additions.

I've been doing quite a bit more searching for sump flow rates, and I've found several threads saying the flow should closely match the skimmer gph. My skimmer is a Reef Octopus NWB 150 with approx 530 gph rated flow. So maybe around 500 gph through that part of the sump would be good? I have really not much way to measure the flow rate. Any suggestions, other than seeing how long it takes to fill a gallon jug?

 

[mcarroll]

I would never add a valve or any other obstruction to a drain.

Use any container you can fit in to collect water from your drain plumbing - it may have to be small but don't worry about that.

Collect water for 5 or 10 seconds. Measure the volume of water collected - convert to gallons as needed. (e.g. google "132mL in gallons")

To get GPH just multiply that volume by 720 if you collected for 5 seconds, or 360 if you collected for 10 seconds.

And yes ~500 gph will be more than sufficient. (Around 300-350 is all it would take.)

-Matt


Sent Via the R2R Forum APP

 

[AZDesertRat]

Never restrict the overflow, the return pump will control the flow rate of the overflow and level in the display to some extent along with the adjustment up and down on the internal part of the box.

 

[Tphill]

mcarroll, I guess that is the cheapest way to measure flow.

AZDesertRat, I think I understand. If you keep the water level closer to the bottom of the 'screen', there will be less volume flowing over. Will also mean in the event of a power outage, there is less water that will flow into the sump, although I think I'll have enough room in the sump to handle more.

Thanks for the replys.

Ordered the pump Thursday. It seems it on a pre-order basis, will be 3 weeks. I should have just about everything else by then and maybe be ready to put water in the tank!!