Close Loop Head loss
 

Ok, for the plumbing guru's.

I forget.. Do you lose pressure / GPH in a closed loop system?

I want to make a pretty complicated closed loop with a series of outlets inside the tank. There will be a single bulkhead coming into the tank and then multiple T's, 90's, 45's etc.

Will the Reef Central head loss calculator give me the total GPH I will be left with or is there a different calculator I can use?

I am trying to achieve a 40x turn over rate in my 34gal cube. So I need to match my pump and this CL system pretty well.

yes but only as much as from the position of the pump and and the water height in the tank.

I thought that was offset by the head pressure from water height pushing IN on the pump intake?

I would say the head pressure loss due to height would only be the difference in heights between the water height in the tank and the height of delivery to the tank.

CL outputs often enter the tank by going over the top edge...In that case, if you turn the pump off..the water would sit in the output pipes level with the tank surface because head pressure through the pump would push it there even if the pump weren't on. The only pressure the pump works against would be the final few inches or so over the top of the tank.

If you inputs enter the tank below surface level (as mine do), there should be no head pressure loss at all.....due to height.

It would also be typical for the outputs to be smaller dimension pipe and have a lot more elbows etc. I think the elbows would cause a flow reduction...

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You are correct untamed. There will be little head loss because of actualy water pressure. The loss of flow will come with the number of elbows and pipe diameter restrictions you place on the system. Reef Central's head loss calculator will be able to determine your pressure loss in that regard.

Oh ok. .I see... so is there a way to balance the flow to the outer edges of the CL? Also, where can you find that grey schedule 80 pipe? I figure that would look a lot nicer than the white stuff.

You could do what I did....paint cheap pipe. Sched 80 stuff is really expensive. Corix can supply you with the pipe you need. Ask for class 200. You don't need Schedule 40, the class 200 is thinner walled so you have larger diametre opening for the same size pipe. Easier to work with also. You aren't running the kind of pipe pressure that would require sched 40 or 80.

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Valves are probably the best way, plus you will be able to adjust each output individually if you want. I don't have any, and I wish I would have installed them for the versitility they would have brought to my CL. As it stands, with not valves, I get more pressure coming from the furthest outputs of my manifold. My guess is that is where I have the highest back pressure, but maybe someone else can shed some light on that.

OK, so where is Corix? Also, what type of paint do you use for the pipe? I do like the grey of the sch 80 stuff.. maybe black would be nicer.

I was going to use lock line at the outlets, using valves on each outlet might be expensive and un-sightly. I am figuring atleast 10 - 15 outlets.

Could I use a reducer at the end, so say, 1/2" at the end outlets and 3/4" in the middle to balance it better?

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10-15 outlets? What kind of tank, and what kind of pump are we talking here. I'm curious now.:biggrin:

I'm using 3/4' locklines on mine which work pretty good for my dart. (3600 gph) I only have 6 of them though.

It is a 34gal cube. I am going to use a Quiet One 4000... Using the Reef Central head loss calculator it says I will be down to about 700 or so gph with all the elbows etc etc.

I will try and post a pick of what I am thinking of doing.