Return line flow director

[Fijiwigi]

I just recently did the plumbing on the return line from my Mag7 to the tank. I used 1/2" PVC pipe with shut off valves etc... My question is does anyone know if they make a flow director that attaches to 1/2" PVC pipe. As of now the PVC connects to 1" tubing with an adaptor and the tubing connects to the flow director I bought from DR Fosters&Smith.( http://www.drsfostersmith.com/product/prod_display.cfm?c=3578+10090+14680&pcatid=14680 ) It looks kinda tacky and Is not very stable. I would prefer if the pvc connected directly to the flow director and I eliminated the tubing. Any thoughts on return line plumbing would be appreciated. Thanks. :?:

 

[dnjan]

I know it is too late, but 1/2" pipe is pretty small for a return line. I started with 3/4" and a Sen700 (about the same power as your Mag7), and after a few years the flow seemed significantly reduced. When I started taking the return piping apart to make some changes, I found that I had an accumulation of material inside the return pipe, reducing the diameter about 3/16". Replaced the old 3/4" line with 1" line and have much better flow.

So, if it isn't too late, I would try for at least 3/4" line for your return, and possibly larger if you are able. Also, try to use sweeps or spaflex rather than elbos.

Back to your original topic - by flow director, I assume you mean the swivel nozzles like those seen on loc-line, etc. I seem to remember getting some of those in the misc. parts package when I bought a submersable pump. You might see if there is a local reef club, and if there is ask the members if they have a spare end like you are looking for. Reef club members are invariably helpful and generous.

 

[MC Lighting]

that looks like locline fittings for the nozzel if so I have some 1/2" locline to female thread adapters that are 1/2" but you woul dhave to make your own u-tube from PVC... Also as stated I would conisder 3/4" over the 1/2" with any kind of flow you would be surprised how much flow loss you gain in the plumbing.

 

[Fijiwigi]

I would think that with smaller pipes you would get more flow because of more pressure. The larger piping would mean it would have to pump more water up the return line to reach the tank. Also the threading on my mag7 is 1/2" threading. I would have to get an adapter to go from 1/2" threading to 1" threading is this correct. Also on a side note a 46bow with a mag7 with the 1/2" PVC is massive flow it is actually too much I think for the refugium section in my sump. But to think out loud here, correct me if I am wrong the water in the refugium zone seems to stay put and the pressure flows water over the top of the refugium chamber and the flow is only intense in the upper portion of the refugium section.

 

[dnjan]

With a smaller outlet, you have higher velocity, not more flow. In fact, you will have less flow, because headloss is proportional to velocity squared (or worse, if you have turbulent flow). So, most people want to minimize headloss (and increase total flow) with larger piping, and then use a smaller outlet to achieve higher velocity at the end.

Also, ideal flow in a tank is often quite different than ideal flow in the sump. Various bypass approaches can be used to create lower flow in a portion of the sump (for example, the refugium section).

 

[Fijiwigi]

With a smaller outlet, you have higher velocity, not more flow. In fact, you will have less flow, because headloss is proportional to velocity squared (or worse, if you have turbulent flow). So, most people want to minimize headloss (and increase total flow) with larger piping, and then use a smaller outlet to achieve higher velocity at the end.

Also, ideal flow in a tank is often quite different than ideal flow in the sump. Various bypass approaches can be used to create lower flow in a portion of the sump (for example, the refugium section).

I really like the flow in the tank I am worried about the refugium flow with the intense tank flow since the refugium should be mellow flow. My refugium baffles are about 10" high with teeth cut on the top. If I have my mag7 flow at full blast will this jeopardize the amount of time needed for the macroalgae to do its thing. I guess that is the question I am after here. And the first part of your reply does make sense to me thanks for the response.

 

[kgross]

With 1/2 pipe on a mag 7 you will be getting less than 300 gph of flow. You need to redo that with 1 inch pipe if you want to get more than 400 gph out of that pump.

Kim

 

[dnjan]

If I have my mag7 flow at full blast will this jeopardize the amount of time needed for the macroalgae to do its thing. I guess that is the question I am after here.

Depends on your macroalgae. Chaeto likes enough flow to keep it moving around.

 

[mfinn]

If I have my mag7 flow at full blast will this jeopardize the amount of time needed for the macroalgae to do its thing.

The water can't rush past it too fast. It's in the water, it's going to "do it's thing".

 

[dnjan]

Basically, all the water flowing past is equally "dirty". But if you don't have enough flow, the algae will absorb the nutrients faster than they are replenished by new "dirty" water.

 

[Fijiwigi]

So, can someone explain to me piece by piece. How you plumb the return line. From the 1/2" threading on the Mag7 till it reaches the tank. I understand the PVC pipe part. Still a little fuzzy on the part where you make 1/2" threading into 3/4" or 1" threading do they sell an adaptor for that. And I want to know how exactly you convert the PVC into the flow director is it Locline plumbing ordered online or can I go to the hardware store and get what I need and get it done today.

 

[dnjan]

They make adapters.

I would get a 1/2" pipe thread to 3/4" slip connector. And then a 3/4" true union.

Connect the 1/2" pipe thread connector to your pump. Then glue that to one side of the true union (you may need a short, approx 1-1/2" long, piece of 3/4" pipe if the connector you got was 1/2" male pipe by 3/4" female slip.
Then connect 3/4" PVC (or preferably 3/4" spaflex, which is flexibe PVC) to the union and take that up and over the back of your tank for the return.

I'll let somebody else let you know where to get the locline.

By the way - in case you are wondering why I suggested the true union at the pump - when it comes time t take the pump out for cleaning, the true union will make it much easier to remove the pump.

 

[kgross]

You will want to get a bushing that goes from 1/2 inch thread to 1 inch slip, that will be screwed onto the pump, then put about 4 to 6 inches of 1 inch spa flex (to absorb the vibration's, Then do either the 1 inch true union ball valve, or a 1 inch union followed by a 1 inch ball valve. Then you will need a 1 inch elbow to move the pipe from the pump to behind the tank a short piece of pipe, another 90 degree elbow, to turn the pipe back up after you get it out of the tank, then a long piece of pipe to go up to the top of the tank, a 90 degree elbow to go over the top of hte tank, a short piece of pipe, another 90 to turn the pipe down into the tank, then another 90 or 45 degree elbow to point the outlet where you want. If you want this last elbow/45 can go 3/4 inch threads so you can screw in lock line to adjust the direction of flow, but you don't need it.

You can do it in 3/4 inch like Don suggested, but you will gain over 50 gph out flow out of your mag 7 if you move up to 1 inch over the 3/4 inch pipe.

Kim
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