Flow.

[Samper]

I didn't want to hijack reeflands thread anymore so I started a new one. My 75 has dual overflows in it with 1" bulkheads. I know it can handle more than a mag 9.5 for a return and have been advised elsewhere that an 18 or 24 is in order. I was also advised that 4 mj 1200s on a wavemaker is in order along with atleast 1 tunze 6000 on a controller. This would be a ton of flow but that's what I want just don't know if that setup is the best idea. How much water can the 1" bulkheads handle? I think I'd like to go with a pump about 150gph less than the total gph that the two bulkheads can handle.

[Ninong]

My 75 has dual overflows in it with 1" bulkheads. How much water can the 1" bulkheads handle?

Each 1" bulkhead could possibly handle as much as 800-900 gph but there are other limiting factors, such as the flow rate of the weir at the top of the overflow compartments and whether or not you are using Durso style standpipes, which increase flow.

The question you should be asking first is how much flow can your sump handle. Is your sump large enough to handle 1600 gph? Is there any possibility at all that either drain could become partially blocked? What sort of standpipes are you running?

[Samper]

The overflows do have the durso pipes and I don't see how the overflows themselves could ever become clogged but then again I guess it could happen. I'm having trouble finding pvc fittings for the bulkheads to plumb the two together but I'll figure something out.

The sump I'm having built has only two compartments but it's going to hold about 50 gallons. One compartment is for the skimmer and the other is for the return. The two will be seperated by 3 over under baffles.

[Ninong]

If your sump is that large, it can handle whatever your two 1" bulkheads can handle. I would suggest you not exceed about 1400-1500 gph through the two bulkheads just to be on the safe side. You can add just about as much additional water circulation via Tunze Streams, etc., as your heart desires as long as you don't have a sand bed and don't plan on keeping anything that does not tolerate a lot of water turbulence very well.

[Samper]

Awesome. This system will be sps dominated with maybe a few lps. Sounds like I should look into atleast a mag 18.

[Reefland]

With 2 overflows with 1" drains, the only limiting factor may be bubbles in the sump. The baffles should eliminate them though.

[Samper]

Score

[Poseidon]

My CPR overflow has 2 1" bulkheads in it and I matched it up with a Mag 12, seems to be a perfect match, I run both WIDE open and have no problems...

[Samper]

Could it handle an 18 do you think?

[Poseidon]

I don't think so, sometimes when a snail or 5 crawl in it slows down the overflow pretty good, causing my water level to rise slightly in the tank. I think the extra 600 GPH would cause the same problem. BUT I don't have durso standpipes either, maybe with them it would be okay... I know the MAG 12 works great though...

[Reefland]

A siphon overflow is going to handle less flow than a drilled overflow too; got to keep the siphon in mind.

[Samper]

Now I'm confused......it's drilled with a bulkhead but also has the pvc durso pipes.

[Ninong]

Now I'm confused......it's drilled with a bulkhead but also has the pvc durso pipes.

Scott is talking about a hang-on siphon overflow. They sometimes have modified standpipes called Stockman standpipes but sometimes they don't. Maybe Scott knows more about your setup than I do because it never crossed my mind that we were talking about a siphon overflow in this thread. All of my advice was based on standard corner overflows with the bulkhead holes drilled in the bottom of the tank.

Where exactly are the drain bulkheads in your tank? Are they drilled in the bottom of the tank? If so, then you do not have a siphon overflow, you have regular corner overflow compartments. Of course it is possible that you could have holes drilled in the upper back wall of your tank that drain into a hang-on overflow compartment behind the tank. That's something else entirely and not a siphon overflow.

I'm really confused now because I don't know where this talk about a siphon overflow came from???

[zhenya]

George, I think it started when Mike(Poseidon) posted about his SPR overflow box and MAG-12, then Scott replied, I think meaning to say that siphon overflow box(SPR in this case) will handle less flow then a standard drilled overflow. I hope I'm correct in my thinking becouse I'll get confused soon too

[Samper]

Ok to clear up the confusion........my 75 has two corner overflows with 1" holes and bulkheads installed at the bottom of each. The shop that drilled it didn't have the plumbing at the time but they are on the way now. From what they describe it's a cane shaped pvc pipe that installs on the inside of the overflow box and attaches to the bulkhead. When they get here I'll get a pic up.

[zhenya]

That sounds like the Durso's standpipe design to me.

[Samper]

That's what it is but all the talk of a siphon and what not got me confused.

[Ninong]

Gene, I guess that's where the confusion came in. I guess Scott's talking to Poseidon and not Samper???

Samper, you can see pictures of a Durso standpipe on Richard Durso's website: http://www.rl180reef.com/frames.htm

[Samper]

I honestly at this point know if the confusion was my fault or not....anyway the durso is what's in the mail. So a mag 12 or 18?

[Samper]

On the website this is what he says.

"But people have claimed to reach rates as high as 800 to 1000 GPH with 1 inch bulkheads rated for 600 GPH"