What pump size? 2 (1/2 in) and 1 ( 1in)

[kimha]

Hi plumbing experts,

I need your help choosing the right size pump. I just bought a used 300g tank. It comes with 1 center overflow box with the followings:

1 drain hole for water drains from tank to sump = 1.5 in

2 return holes for water from sump back to tank = .5 in each
1 return hole for water from sump back to tank = 1 in

So for the tank out let, it has 1.5 inches outlet

for tank inlets, it has .5+.5+1 in = 2 inches inlet total.

I am not sure if this is enough to support a 300g tank.

I was told I need at least 10 times flowrate for good water cirulation. Which means I need to have 3000 GPH flow rate.

Questions:

1. Can these inlets/outlets support 3000 GPH flow rate? If not, what is the max flowrate can it supports?

2. Which external pump would you suggest for this setup?

Thank you very much for your help.

 

[Edward Smith]

I think there's alot of contreversy over the "10x circulation" rule. I have mine at about 6x an hour and have great results. I believe its much more important to have good internal circulation. If the funds are available, go for closed loops. If not, good powerheads.

There was a reef central article about internal vs external circulation. Does anyone have the link?

 

[Doubledown]

IIRC a single 1.5" drain can handle about 1400 - 1500 GPH.

I am surprised that the holes for the returns are .5" on a tank that size. I would use the 1.5" as a main drain, the 2 .5" as overflow drains and plumb the 1" as the return line (split it in the overflow to 2x.75" lines that go to either side of the center overflow). Get yourself a return pump that runs about 1400 - 1500 GPH (Panworld 200PS or Iwaki 70MD come to mind) after head pressure loss and you should be fine.

As far as tank turnover, there is a debate aboute how much water should run through your sump. I feel you would be best off with the above scenario (1400 gph = 4+ times turn over) and increasing your in-tank circulation via powerheads, Tunzes or a closed loop. Basically I agree with Ed (and wish I had done this on my current set-up).

 

[kimha]

Doubledown - Sorry I got the measurements wrong. The measurements I listed on the first post are on the overflow box it self.

On the bottom of the tank there are 4 holes.

The 2 holes in the middle are 1 3/4in each.
The 2 outer holes are 1 1/4 each.

Without knowing about plumbing, I am guessing after putting in the bulkheads, the 1 3/4 hole becomes 1 1/2? and the 1 1/4 hole will become 1 in?

I am guessing the 2 middle ones are for drain from tank to sump. And the 2 outer ones are returns. With these sizes, how much flow can it support and what pump size would you recommend?

on personal preference, I want to avoid using powerhead as much as possible because it doesn't look nice with powerheads dangling inside the tank.

Thanks much,

Kimha

 

[Doubledown]

The holes drilled into the bottom of the tank IIRC are sized for 2 x 1" and 2 x 3/4" bulkheads (that sounds better). Use the 2 x 1" for drains and 2 x 3/4" for returns. This is the same config I have on my 180 FOWLR. I use a Sequence Snapper (2500 GPH - not pressure rated but only uses 98 watts and is silent) as a return. In additon to the 2 x 3/4" returns in the overflow, I run an additional 2 x 3/4" lines up the back into the tank via SeaSwirls for alternating flow. I have to also restrict the output of the Seaquence pump a bit as well to keep from over flowing the drains (1" drains can handle about 800 GPH each IIRC).

I ran a MAK 5 (1500 or so GPH) as a return pump for a long time, but found it too loud for my taste.

The Panworld or Iwaki listed above would still be a good choice IMO.

It's the drains that will restrict the amount of water you can push into the tank (1500 GPH I think is pushing it). If you want more in tank circulation (depends greatly on what livestock you plan to keep) you have several choices:

1. Closed Loop - requires drilling for closed loop intakes at a minimum.

2. Powerheads in the tank.

3. Use a pressure rated pump like the ones listed above and try to use eductors or penductors on the return lines (there are several threads about these items, but the premise is they use the pressure of the return water to draw in more tank water and multiply the amount of in-tank water being circulated up to 5x).

4. Add a surge tank.

I kept a mixed reef (mostly softies with a couple SPS) in my 180 with roughly 7x turnover for over a year with out issue and keep the same for my FOWLR, but if you want to keep SPS you will have to bump it up in tank with one of the above methods.

Hope that helps alittle.