Anyone know the max flow rate on 750xxl?

[AZMSGT]

Let’s see if I can get it to push more than the 550gph ...

The problem is the Tanks bulkhead fittings are to small. No matter how big the pipe is up to and away from that it’s the limiting part. Then there is the tiny return pipe bulkhead and feed into the tank. It’s all about choke points and restricting flow.

 

[widarecu]

The problem is the Tanks bulkhead fittings are to small. No matter how big the pipe is up to and away from that it’s the limiting part. Then there is the tiny return pipe bulkhead and feed into the tank. It’s all about choke points and restricting flow.

I realize that last time as well, my plan now is to completely by-pass the original plumbing and bulkheads, it will come from behind the tank, I’ll post some photos later once finished ... I think it will work.

 

[AZMSGT]

I realize that last time as well, my plan now is to completely by-pass the original plumbing and bulkheads, it will come from behind the tank, I’ll post some photos later once finished ... I think it will work.

That should definitely do the job.

 

[widarecu]

So I managed to fit 1.5 inch pipe to the Vectra and then reduced to a couple of 1 inch outlets into the tank .... what a difference, managed to go from 2200 lph with the original plumbing to 5500 lph running at 60%.

I can’t push any more flow than that as the overflow can’t handle it, I turned all 3 pipes as return to the sump but running at 60% the water level is less than half an inch of overflowing.

Some photos of the setup, not the cleanest but it’s fine as it’s all hidden in the back.

 

[becon776]

yeah red sea did themselves a disservice by going with metric plumbing. such a huge pita. like this thread though.

any stories of redrilling thru bottom and installing mew bulheads with STANDARD plumbing? pref 1" or 1.5" and replace with standard bulkheads that would be amazing... i dont have the testicular fortitude to try it but thought maybe someone else has.

 

[Al Sayani]

Just curious what is the max flow rate I can achieve using the stock plumbing. Im looking to use the Triton method and they recommend 10x.

I have upgraded all my plumbing to 1 inch but the return still reduces to 3/4 inside the overflow.

 

[Al Sayani]

Just curious what is the max flow rate I can achieve using the stock plumbing. Im looking to use the Triton method and they recommend 10x.

I have upgraded all my plumbing to 1 inch but the return still reduces to 3/4 inside the overflow.

Just curious what is the max flow rate I can achieve using the stock plumbing. Im looking to use the Triton method and they recommend 10x.

I have upgraded all my plumbing to 1 inch but the return still reduces to 3/4 inside the overflow.

Any idea if i drill the sump in the 750 xxl. I have my sump run into the basement and barely getting 380 gph flow to my tank that is appx 15ft above. I just purchased an external pump (Hammerhead Barracuda). Do you know if the sump glass is tempered?

 

[Roughneck]

I know this is an old post, but I'm still trying to figure out why Red Sea claims the stock plumbing to be able to handle 1850gph.

For those of you that are only getting 600-800gph, does your 750xxl have the dual return outlets like the V3 and the new G2? I'm asking because I want to plumb a UV that require 1000gph.

Was the bottleneck the return outlet or the downflow/overflow plumbing?

Thanks for the help!

 

[rsumner]

I know this is an old post, but I'm still trying to figure out why Red Sea claims the stock plumbing to be able to handle 1850gph.

For those of you that are only getting 600-800gph, does your 750xxl have the dual return outlets like the V3 and the new G2? I'm asking because I want to plumb a UV that require 1000gph.

Was the bottleneck the return outlet or the downflow/overflow plumbing?

I believe the old 750XL (non G2) only has a single 1" (25mm) return line and a 1.25" (32mm) drain line. That single drain under full siphon could probably handle 1000+ GPH, but I think the 750 restricts their return lines when it exists their overflow the same way my 525 does. I even read some old posts that the 750 uses the same exact diameter plumbing as the 525, but I'm not sure about that. If you intend on plumbing a UV inline on plumbing that is similar to the 525, you won't get 1000GPH unless you run a really high powered pump. I run a Reef Octopus 8 on my 525 that's rated for 2700GPH @ 18ft head with a UV plumbed inline and I could never get over 500GPH. See my 525 build thread where I go into a lot of these details and spent years redoing my plumbing several times.

As for your comment about Red Sea claiming the plumbing can handle 1850gph: I don't believe they actually claim this. They simply recommend a 1850gph return pump which will usually result in about 1/3 of that flow by the time you account for head loss of the pump and the contribution of their crappy plumbing. The Net: Red Sea plumbing has always sucked IMO which is why they mention it heavily in their G2 series.

Lastly, whatever UV you're planning on using probably doesn't require a minimum of 1000GPH. I'd hate to side-track this thread going off the deep end on UV specifications, so you can PM me and I'd be happy to discuss UV with you. If you are really trying to achieve 1000+ turn over on a single return 750, my suggestion would be to add external returns that come over the back top rim.

 

[blaxsun]

I know this is an old post, but I'm still trying to figure out why Red Sea claims the stock plumbing to be able to handle 1850gph.

For those of you that are only getting 600-800gph, does your 750xxl have the dual return outlets like the V3 and the new G2? I'm asking because I want to plumb a UV that require 1000gph.

Was the bottleneck the return outlet or the downflow/overflow plumbing?

Thanks for the help!

Yes, the bottleneck is mainly the return plumbing. You can get around this to some extent by running a separate return pump on each line (but this presents other challenges). I know someone locally that re-plumbed his returns to a larger diameter and was able to increase his flow from 650-750 Gph to the 950-1000 Gph range (this is obviously a lot more involved and not for the faint of heart).

Your target should be 3-5x flow, so anywhere in the 480-800 Gph range is fine - so my advice is to stick with the stock plumbing because it's a PITA to fine metric-imperial adapters.

As for the UV, you may want to just get a separate pump and loop the flow in the sump (which is what I did) to be able to control the flow better. This is what I did, ie: my tank flow is 650-700 Gph and my UV flow rate is closer to 850-950 Gph.

 

[Roughneck]

Yeah I think you are right, that would be the easiest way. How did you set it up? Seperate pump near the return pump pushing it back to the drain/downflow part of the sump?

Did you noticed a significant difference in algae control with that configuration?

 

[blaxsun]

Yeah I think you are right, that would be the easiest way. How did you set it up? Seperate pump near the return pump pushing it back to the drain/downflow part of the sump?

Did you noticed a significant difference in algae control with that configuration?

I ran the pump from the refugium to the skimmer chamber with the UV in-between. Yes, it makes a noticeable difference with algae and parasites.