How big is too big for a return pump?

thejuggernaut · Jan 12, 2015

If it gets too hot, you can always run it external. Honestly, if you have the room and don't mind a little extra plumbing, external is usually the way to go. Much rather let the air cool the motor block than my tank water. I never picked up on what your sump layout looked like or how your overflow system was designed. Those could have a big impact on what type of pump you needed.

ryleary · Jan 16, 2015

Im copying this https://www.youtube.com/watch?v=t-WBDP7zbQs&list=LLj_kE_z-yIPMQRgZ71I2LBQ&index=5 design for my sump, just started building last night. My return will flow directly up about 6 ft, then a 45 to get out of the wall and then up another 3 ft or so to the top of my tank. And i dont understand whats so bad about letting the pump give off some heat, wouldent that just make the heaters work less and conserve energy?

AZDesertRat · Jan 16, 2015

In winter months yes but may require a chiller in summer months.
Running externally is not always the answer either since many pumps are cooled by the product water circulating through jackets or passages in the motor. About all pumps that can be either external or submerged are this way and they add the same amount of heat to the water either way. External fan cooled motors often have a stainless steel shaft that gets hot and transfers that heat to the water even though they are not product cooled. And most fan cooled motors are much louder than a submerged pump.

Zacco · Jan 16, 2015

I totally agree with AZDesertRat . Let your heaters regulate your water temp. You have no control over the heat dissipation your sump pump is giving off. This is why you purchase a better quality sump pump that run's on less wattage than a cheaper made one that runs on more wattage. You may see a difference of up to 30 watt's between two different model pumps that output the same amount of water. What is better. Spending 80 dollars more on a better quality sump pump that runs at a lower wattage, or buying a chiller later for 300 to 400 dollars just to bring your temp down 5 degree's.

pmorphb28 · Feb 17, 2015

I was wondering, since you have experience is there any way to make the md 100rlt quieter. I've had mine running about 5 hours and my wife is pretty unhappy with the noise. Running it to a 120 tank.

Thanks.

AZDesertRat · Feb 17, 2015

That is always an issue with external pumps. How is the pump plumbed? What size are the sudtion and discharge line sizes? What do you have for fittings and pipe? Is the suction side of the pump a straight shot to the sump so it is not starving the suction and causing cavitation? Do you have a length of vinyl tubing coming off the discharge side to break up any vibration and sound transmission through the PVC? What about the suction side since it is an external pump, is the pump sitting perfectly level and plumb and with all 4 feet flat on the floor or stand so there is absolutely no stress on the pump or piping? If the pump is not sitting float with no stresses this is what we call "soft foot" and needs to be corrected.
Have you tried something like placing the pump on a mouse pad or piece of silicone rubber? Photos would really help.

thejuggernaut · Feb 18, 2015

pmorphb28 said:
I was wondering, since you have experience is there any way to make the md 100rlt quieter. I've had mine running about 5 hours and my wife is pretty unhappy with the noise. Running it to a 120 tank.

Thanks.

http://www.reefcentral.com/forums/showthread.php?t=828812

pmorphb28 · Feb 18, 2015

Thanks a ton. I will get right on this. I had this nauseous feeling when I thought about having to replace a 500$ pump after the first day!

thejuggernaut · Feb 18, 2015

Lol, yea those pumps are bullet proof and work great, but they are LOUD. I had one similar on my 120 and I was just too loud. Heck I got rid of my MP40's cause they were too loud. These new ones have really peaked my interest though.

barnfrog · Feb 19, 2015

Mine is overpowered to run reactors... video of the initial setup below

[video=youtube;GJIXlzC3keo]https://www.youtube.com/watch?v=GJIXlzC3keo[/video]

cmcneil · Feb 19, 2015

You can always tee off the pump near the sump and add a ball valve then the excess unneeded flow can go back to the sumps filter sock or feed reactors or other equipment.

AZDesertRat · Feb 19, 2015

Returning flow to the sump is extremely inefficient, uses more power so costs more to operate, is actually harder on the pump since it is being required to work harder and adds more heat to the water. It is far smarter to install an inline valve on the discharge side to add additional head to the pump so it is not working as hard, creates less heat, draws less amperage or watts and lasts longer. Plus they are usually quieter too.

barnfrog · Feb 20, 2015

Not if the pump is over-powered to begin with. It just bleeds unnecessary flow into the reactors. If you valve the output of the reactors and the return back to the main tank, you will have full control of the flow. The heat and amperage draw is steady and there is no additional noise.

AZDesertRat · Feb 20, 2015

Reactors only use a low volume of water so the small amount you send back through them and eventually to the sump is minimal. When you use a ball valve or gate valve though to dump excess flow back to the sump you are requiring the pump to work harder thus higher wattage and heat gain. When you install the valve inline to the display and throttle it that way you reduce the work required of the pump by adding additional head which cuts the watts or power consumption and in turn creates less heat. This applies to all centrifugal pumps and is spelled out in Bernoulli's Theory and The Laws of Affinity which both have to do with fluid dynamics. It is very easy for the reef hobbyist to prove with a simple $25 Kill A Watt meter. I bought two of them just so I can monitor power consumption and fine tune my systems power usage.

It is a hard thing to grasp if you don't work with pumps and hydraulics for a living and doesn't make sense but is fact.

barnfrog · Feb 21, 2015

I grasp your concept just fine lol. I've been in the hobby for 20 years and I've run a coral and fish wholesale business for 10. I've designed and built this type of system many times with no heat or draw issues. To test your concept I turned off the flow to the reactors and ran he pump as is (since your first response). I also took a therm reading from the pump (reef flo hammerhead). I just looked at the charts on my apex and there was no difference in amperage draw. The therm reading from the pump is exactly the same. With that said, I think your concept is sound. However, that is only assuming that you are trying to get the same amount of flow back to the main tank. The people that go with this method use over powered pumps. Meaning if we want 100gph return to the main tank, we will get a 125gph pump. We accept the fact that the flow is reduced by bleeding the return into the reactors. We don't expect the same amount of flow back to the main tank. Now if we did, then yes, we would need to push the pump past its normal operating parameters which would cause higher draw and excess heat.

I don't mean to argue with you. It's just a bit annoying when someone writes "it's smarter to..." I hope you understand

AZDesertRat · Feb 21, 2015

It is not a concept, it is the laws of fluid dynamics at work.
You did not do the one simple thing that proves this out, measure the electrical consumption. You can pick up a Kill A Watt meter at the hardware store for around $25 and run it both returning excess flow to the sump and throttling the flow inline back to the display. The second option will show reduced wattage meaning the pump is working less and creating less heat due to electrical inefficiencies which in inherent with all motors.