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snakeplisken 11-19-2012 05:00 PM

Closed Loop filtration and pump placement
hey guys, new to the forum but not to tanks. Looking to run a filter in-line on a closed loop. looking for suggestions where to put the pump. Should I push the water through (pump before filter) or pull it through (pump after filter.) Pump is a Little Giant 3MDQ-SC.

Thanks for your input,

Hoppy 11-19-2012 07:08 PM

That is exactly what a canister filter is, and some of them are cheaper than the cost of any workable DIY version.

snakeplisken 11-20-2012 02:51 PM

Thanks a lot Hoppy, I appreciate it.

I understand what a canister filter is, but I was looking for suggestions on where I should put my pump, before or after the filter. The tank itself is a 65 Rimless from GlassCages, and I drilled it for closed loop already (used to be a reef) Trying to keep the plumbing very simple, and was really trying to not go w/ a sump setup.

Thanks again

Hoppy 11-21-2012 01:28 AM

I think the pump should work best ahead of the filter. If it is after the filter, and the filter gets a bit clogged up, the pump may cavitate from the low inlet pressure. But, if the pump produces a low head pressure, it might not have enough oomph to push water through the filter and lift it back up over the top of the tank. So, it depends on the pump parameters.

From "Little Giant 3-MDQ-SC (581506) is a Magnetic Drive Aquarium Pump 1/15 HP, 115V, 6' power cord - SC Quarium Series for semi-corrosive salt solutions and chemicals, designed for in-line saltwater and freshwater aquarium circulation and filtration applications.
Little Giant 3-MDQ-SC 'Quarium Series features a leakproof, seal-less magnetic drive and a more quiet operation for freshwater and saltwater aquariums. Little Giant 3-MDQ-SC has 1/2" MNPT discharge and 3/4" FNPT Intake with head capacity of 18'. This is a pressure applicable pump. The MDQ model was built to handle back pressure very well and is recommended for high head heights or for canister filtration systems."

snakeplisken 11-21-2012 03:47 PM

thanks again hoppy! I'm in the parking of Lowes right now. grabbing some brackets fire the stand, then plumbing begins!

the4x4hoss 11-23-2012 03:07 PM

All water pumps push more efficiently than they pull.

xmas_one 11-23-2012 04:42 PM

Pumps push. Never pull.

Optix 11-23-2012 05:46 PM


inkslinger 11-24-2012 02:29 AM

{Push Flow} Pressure type aquarium pumps handle back pressure better and can be used for almost any application. Especially recommended for high-head situations or when using cartridge (pressure) filters like Nu-Clear and Red Seas canister filter.

{Pull Flow} Non-Pressure type aquarium pumps are best suited for circulation only - that is, where water encounters very little back pressure--for example, returning water from a sump. Excellent where a high turn-over rate is desired like wet-dry and sumps.

snakeplisken 11-26-2012 12:00 AM

thanks again for all the responses fellas! It makes sense that pushing would be more efficient, kinda just wanted you all to collaborate that for me.

snakeplisken 11-26-2012 07:56 PM

I was looking up those canister filters and I'm strongly considering the NuClear 522. think it's overkill for a 65? I would consider a fluval or something similar, but it would still have to be hard plumbed, and I would still have to run a closed loop with the little giant. tank has 5 holes drilled in it that need to be used. thoughts??

wkndracer 11-26-2012 08:26 PM


Originally Posted by xmas_one (Post 2087244)
Pumps push. Never pull.

True true but I decided to go with a Little Giant 3 MDQX SC here and what a horse of a pump! Flow is not an issue used as a return pump on my DIY sump. In 3yrs I checked the impeller housing twice and regretted it. Checked twice and it was clean except for tannin staining both times and no wear.
* remember to drop oil on the bearings :smile:

O2surplus 11-27-2012 05:14 PM

39 Attachment(s)
Take a look at the Ocean Clear 318. I've got 2 of them on my 225, and love them. They're really easy to hard plumb and will go forever between cleanings. These filters have a screw on lid that is much easier to deal with than the Nuclear's Clamp/screw top.

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