Return Pump Size?

[alohami]

I am hoping you can help me determine what size return pump to use. It will be a 65g mixed reef, built in overflow with Durso standpipe, and either a 20 long or 29g sump/fuge. I'm thinking about using the Tunze 6025 powerheads, so that would be 1320gph if I had two of those. If I used a Mag 7 at 700gph, that would give me 2020gph/hour total, and percentage wise that would be 31% turnover.
Is that adequate, or should I go for a stronger return? I've only had HOB equipment before, so I have no clue what I'm doing when it comes to overflows, fuges, etc. Any suggestions and advice is appreciated!

 

[coachklm]

you need to to evaluate you drain size,, you cant pump more into your tank that you cant drain down fast enough.

 

[alohami]

Okay, like I said, I'm a totally newbie when it comes to plumbing. Is that determined by the size of the pipe?

 

[prime311]

Yes, by the diameter of the bulkhead/pipes. Although you can use a stronger pump if you redirect some of your return flow back into the sump/fuge with a T pipe and a couple of ball valves.

 

[alohami]

I would have to measure the actual pipes (can't find the darn tape measure at the moment), but I was told the bulkheads are 1-1/2" and 1-3/4" respectively. The return line is the smaller of the two, if that matters.
Here is a picture of the bulkheads if that helps:
I've always wondered what the point is of diverting the water back through the sump. I understand it's to reduce the flow back to the display, but is there any benefit to this, or is it just a way to deal with an over sized pump?

 

[prime311]

Well if you have a refugium in your sump on one end and don't drain your overflows into it at all, then its also a way to get water flow into your refugium. The main use though I think is to handle an overly strong pump.

 

[alohami]

That makes sense, I think.

Can anyone make any recommendations on the return pump size? I am trying to keep my eyes out for a used one I can pick up at a good price, so I'd like to know what I should be looking for. Thanks!

 

[prime311]

A Mag 9.5 would be good with that size of overflow. If the standpipe is 1.5 that would be over 1000 GPH.

 

[zeroc0o0l]

I have this setup on my 72 bowfront. Mag 9.5 for the return and it works well here link to the refuge
https://forums.saltwaterfish.com/t/312134/30-gallon-refugium
and the tank
https://forums.saltwaterfish.com/t/312009/55g-to-72g-bowfront-diary

 

[alohami]

Okay, PVC is measured on the OD, right? I just measured the overflow pipe, and it is 1-1/4" OD. The return is 1" OD. Is it normal that the bulkheads be oversize? I'm not sure on the measurements on the bulkheads; I just went by what the guy told me that I got it from.
So would a Mag 9.5 still be a good choice, or would I need to drop it down to a Mag 7 since my overflow is a bit smaller?

 

[prime311]

Well someone with more experience might have a better answer, but I believe your water flow is limited to the size of your smallest pipe so you're looking at about 800GPH of flow from the standpipe. Considering the loss of flow from pushing the water up the return and you'd probably still be fine with a 9.5, a 7 also would work but that means you'll need to get more water flow from your powerheads.

 

[ameno]

keep in mind a mag 7 will not give you 700 gph of flow, it will be less depending on the height it will pump up, elbows, fittings and any horz. run that you might have. I think from what I've seen that you actually have a 1" drain and a 3/4" return, the pipe ID is what you measure by. If thats the case then your drain will produce around 600 gph for an average. That is if there is only one drain and one return. So a mag 7 should work ok but not give the max. flow of 600 gph. mag. usually calls for 2x there discharge dia. for max. flow. a mag 9 might be the better choice and go with a 1" return line out of the pump to the tank.

 

[alohami]

Yes, I actually do have a 1" drain and 3/4" return. I just went to look things over again, and it actually says that on the bulkheads. I don't know where the guy I got the tank from got 1-1/4" and 1-1/2". There is only one drain and one return in the left-hand corner.
Since it's already drilled, and I have the bulkhead and return PVC, I'd rather not mess with increasing the size of the return if I don't have to. Do you all think it's necessary to increase it, or would it be okay if I compensated with extra flow from powerheads? I did know about gph loss, but I forgot that minor detail. lol. It sounds like my best bet might be a Mag 9 as long as that wouldn't be too much for a 3/4" return.
I really, really appreciate all the help!

 

[ameno]

I think what you have would be fine, you can size up to 1" on the return from the pump discharge and then size back down at the bulk head, and do the same on your supply by going up there to 1.25" or 1.5", this would give less restriction on the flow and give a better flow. and using the mag 9.5 it should give you the max. flow that you can get. just be sure and put a valve on the discharge, that way you would have some adjustment if needed

 

[joncat24]

I just set up a 65 with the same drains....I am using a quiet one 3000 for the return pump. I have a ball valve on the return, it is almost all the way open. You dont need to get too large of a pump, cause the drain will only handle so much. There is no sense in wasting money on a pump that pumps 700-900 gph, just to throttle it back. Just my opinion though.
the flow in the tank can be made up of powerheads, I am using two koralia #3's in mine, and getting very good flow throughout the tank.

 

[ameno]

depending on the skimmer you are using and the size of the fuge you may want the most flow you can get with the 1" drain, a mag 7 will give around 400 gph flow with a 3/4" return, ball valve, union and a few 90's at 4' lift. a 9.5 will be around 630 gph. As far as what you can get out of the drain will all depend on how it is pipe up, staight down and up size the drain you shoud get a bit better then 600 gph. which means a mag 9.5 would be pretty much equal to the drain gph. But then again it all depends on what flow you want.

 

[alohami]

This is all so helpful! I really appreciate it! I just need clarification on sizing up the lines. Are you saying to just increase the line below bulkhead, or would it need to be increased both within the overflow and below the bulkhead to do any good?
The sump is a 20 long with three chambers and bubble traps separating each section. The middle chamber will be a fuge. I am planning to position it directly below the overflow, so the drain line could go straight down. Although, I thought I read somewhere that you don't want perfect verticals, so I'm not sure if this is a good idea or not.
The skimmer is still undetermined at this point. I'm thinking something along the lines of a AquaC EV-120. The skimmer chamber is roughly 6" x 12" so I need something with a fairly small footprint. I'm open for any and all suggestions!

 

[ameno]

Guess I don't fully understand how your sump is setup, normally you would set up with either dumping into the skimmer area and then flowing thru the fuge and then into the sump return area, or the way I set mine up, is with the sump in the middle, fuge on one side and skimmer on the other and I tee off the supply to each compartment, this set-up requires more gph for supply.
Normally as a rule of thumb you want to shoot for around a 1.5x the gph of what your skimmer pump gph is. so if your skimmer is 500gph then shoot for around 700 to 800 gph supply this helps compensate for blowby of your skimmer pump and will help your skimmer to be more effecent. and if the compartments have a seperate flow like I have mine then you can set your flow rate for the fuge also, which I have mine at around a 10x turn over of the fuge, I think 10x should be min. 15x would probably be better. Hope all this makes sense.
As far as upsizing the supply lines, the more you go up in size the better flow you will get, so if you upsize both sides of the bulkhead then you only have a small restriction in the line which is were the bulkhead is. so any amount of increasing the line size will help, best flow would be both sides of the bulkhead.
If you go with the mag 9, I would just use 3/4" return all the way for the return or 1" max. 1" would give you around 750gph. 3/4" around 640gph. up sizing the line on both sides of the bulkhead on the supply might get you to 750 gph if it's flowing straight down

 

[alohami]

Yes, it is making sense, thank you! That's good to know about matching flow to the skimmer size. I didn't know about that at all, but it makes sense. My sump will be set up the "normal" way -- left will be overflow drain and skimmer, middle fuge, and right return.
I'm thinking I would have to use flexible tubing to increase the line sizes so it could be clamped to the bulkhead, unless there is an adapter of some sort that could go in between to transition between the different sizes. That would be easy enough except on the drain line inside the overflow. I want to go with a Durso standpipe for my drain, so I would have to have some sort of an adapter in order to fit the bulkhead.
I'm almost wondering if I should just go with what I have and see what the flow is like. It doesn't seem like it would be too difficult to change it out and increase it if it was needed. I'm guessing that I should have ball valves on both lines in order to regulate and/or shut off the flow, but do I need a check valve too to prevent back siphon?

 

[ameno]

Yes you would want ball valves, and I would not use any check valves, they tend to stop working with salt water. but on your return if it goes into your overflow box then it will stop the back syphon once the water level gets below the teeth on the box. but if the return is goin over the top then you would need to drill a 1/8" hole just below the water line for a syphon break.
I assume you bulk heads are threaded if so you can use a standard bushing to increase the size. any piping hardware store would have them, it would be male threaded 1" to slip on 1.25" or 1.5". I would also put a union and ball valve down by the pump discharge to easily remove the pump if needed.