How do I figure what size return pump i'll need (1 Viewer)

[KIPS]

I am getting the CPR 102 overflow box. How do I figure what size return pump I will need? Max flow rate for that box is 1200 GPH, and the top of my tank measure 4' 2.5".

Any suggestions?

 

[cliner]

What's the tank volume? That along with your CPR, plumbing capacities should help determine. What size plumbing are you going to use?

 

[KIPS]

tank is a 90 gal bowfront. Is less waterflow ideal, or this all just a personal preference? I personally feel like 1200gph is a lot. I don't want to flush the livestock around. I found the the overflow on WTS section here and my sale still pending. I have every intention on picking it up on a recomendation from a friend on here, but that was given before they realized it had two bulkheads and the amount of flow. It has 3/4" tubing on it now.

I guess my first question should be should I stay with the 1200 gph ot try to reduce this?

My thoughts are I can reduce the flow by smaller plumbing or seal off one of the bulkheads on the box to cut the flow in half.

 

[trb]

The flow is just what the maximum is. It will only flow what is being pumped back into the tank. If you use a 900 GPH pump, the overflow will only flow 900 GPH, if you use a 600 GPH pump, it will flow 600 GPH, etc.

For corals I believe higher flow is desired. I would think a return pump with something in the 700-900 range would be OK, just don't want to max out the overflow, just in case of accidental restrictions. Look at the pumps and find the flow at a head height of 4-5' and that should be a good number to use. I have a Quiet One 4000 on my 60 gal with 29 gal sump and at 5' my flow is about 700 GPH.

 

[trb]

Just looked up a couple of others. Lots of guys recommend the Eheim pumps, but they are a bit more money. The 1262 ($130+ new) flows about 700 GPH at 4'. A Mag Drive 9.5 ($90+ new) flows about 800 GPH at 4'. But if you wanted a lower flow, just get a smaller pump and use the recommended return line plumbing size.

For sure use both of the overflow outlets, one can be the primary and the other can be a backup if you are using a lower flow return pump. Better to be safe than sorry with a wet floor. You might have some water level bouncing around in the outer overflow box with a lower flow pump, (and some associated noise) but then you could put a valve on the main drain line to slightly restrict it and keep the water level more constant. But whatever you do, I would not cut the lines down to only one. You have the second line, use it as a backup. You can make one of the drain bulkheads higher with some pipe or tubing and then it will only be used if the primary backs up.

Basically you will have to tune it to get the flow right and cut down on any noise, but it should not be a problem.

 

[KIPS]

Thanks for the help trb. I guess it is common sense now that you have opened my eyes. I am getting the mag 9.5 with it.

Plumbing Question though:

would you T the two drains into one main drain I can adjust the flow, or would you run the two directly to the sump and put valves on them seperately? Is pvc or hoses preferred?
thanks again

 

[trb]

I would run them separately. You don't want any obstruction to totally block the flow. I used a combination of PVC and flex tubing on my internal overflow. My main drain is flex since it is used all the time and the flow is better without all the PVC elbows and joints. 90 degrees do reduce the flow a bit more than a gentle bend, but you can use 45s also. Since my seconday is used only occasionally, it is hard PVC dropping directly into the sump. But seeing as yours is a HOB overflow, I would use flexible tubing for both so you can easily move it around for cleaning the tank.

Personally, I would just set it all up without valves at first and see how it runs. Then if you need a valve to adjust the flow, add it. If you get the spa flex tubing, the solid white one, you can use PVC glue to put in a valve. Make sure you can take it all apart either with PVC screw together unions or hose clamps for cleaning.

Good luck! I probably made a dozen trips to Home Depot & Lowes working on my plumbing!

 

[angel4]

Thanks for the help trb. I guess it is common sense now that you have opened my eyes. I am getting the mag 9.5 with it.

Plumbing Question though:

would you T the two drains into one main drain I can adjust the flow, or would you run the two directly to the sump and put valves on them seperately? Is pvc or hoses preferred?
thanks again

You do NOT want to put a valve on the drain line, that is not how you control the flow rate.

Let's say you do that and lower the flow down the drain to 600 gph.
Let's say your return pump can pump 700 gph back to the main tank.
Where do you think the water will go? It will overflow your main tank onto your floor.

If you want to control flow, control the return line.
Better yet, get the right size pump and you don't have to bother with valve and control.


What is the right size of pump?
It's anything less than the maximum that your drain can handle.
What your drain can handle is dependent on its diameter.

According to this calculator, a 1" drainline can drain 600 gph, a 1 1/4" drainline can drain 900 gph

http://www.reefcentral.com/calc/drain.php

You said your overflow box can drain 900 gph? Does it have a 1 1/4" drain line?
A mag 9.5 is rated at 950 gph, that is more than your drain can handle. You will have water on your floor.

 

[KIPS]

The overflow box has 2 - 1" drainlines and it is rated for 1200 gph. I figured there is no right as long as it less then that.

Now I just have to figure out the plumbing to and from, and if I want to split the return into two flows.

Does anyone have suggestions on that, or pictures I can look at? I am pretty handy, just need an idea of how to run the plumbing and how I should put the heads in the water, what angle etc...like 2 in the middle pushing out or the opposite with them on the outside pushing in, or if I should just do one to counter the powerhead I have in there.

 

[angel4]

If you have 1200 gph drain then you are ok.

As far as designing the return, it all depends on what you want the flow to hit.

Splitting the return into 2 will give you more options. You can also use a loc line so you can adjust the direction of the flow.

http://www.locline.com/products/index.html

 

[KIPS]

I have seen those and that is exactly what I want. Is there a LFS or someone local that sells these. I would like to find out what pieces I need and get tips rather than buying parts blind.

Thanks you very much! I have been wondering how I was going to acomplish this. The idea of PVC in the maintank has been bothering me so much!!! lol

 

[angel4]

I am pretty sure City Pets or any good size store would carry them. They are very common.

 

[KIPS]

Cool. I'll check with them. Thank you