Return plumbing question

[griffinrl]

I have aquired a 185gal reef ready setup. The sump is about 30 gal and has a Mag 7 and Mag 12 connected to the returns. The tank is dry now as I plan on doing some hard pvc work before I get it percolating. My question is do I really need both of those pumps? One on each return or could I split the Mag 12 return to both sides? I have built in overflows on each side of the back. Would a Mag 12 be strong enough to give enough tank turnover? I'd like to use the Mag 7 on a skimmer if possible. Oh the two overflows have standpipes that sort of look like an inverted "J" so I'm guessing this is a durso type standpipe if that makes a difference.

 

[dnjan]

What size are the overflows? I suspect the two overflows will just handle the mag12 return.

You will probably need additional flow in your tank, but not necessarily flow that is going into your sump.

 

[griffinrl]

Don,

I roughly measured the overflow boxes and they are about 6" x 10" rectangles in each corner of the back of my tank. I believe I have 3/4" return lines on the pumps and 1" on the overflows. I don't really know a bunch about flowrates, gph, etc. but I'm thinking a Mag 7 and Mag 12 together might be a tad bit of overkill?

 

[dnjan]

Two 1" overflows will barely handle the flow from the mag12 (depending on how much headloss there is in the return lines).

Use the mag7 on the skimmer (assuming it is enough for the skimmer you have).

 

[griffinrl]

I planned on doing some hard pvc plumbing for it. Right now the Mag 7 is connected to the return on the short side of the tank. The head is probably 5' maybe using flexible hose. The Mag 12 is on the same side of the sump as the 7 with flexible hose running to the far return with a head of maybe 8'? I was hoping that I could just run both returns with the Mag 12 (split the return water from the sump to both return hoses on each side of the tank) and have both overflows hard plumbed to one outlet into a filter sock on my sump. With appropriate valves and such.

Also I have 2 Koralai PH's for additional current in the tank.

 

[dnjan]

You probably will want to run at least 1" pipe for the return so that you reduce headloss. With that, the Mag12 should provide enough return.
What size (and type) of flexible line is being used for the returns now?

 

[griffinrl]

For water out of the overflow to the sump it appears to be 1" in diameter. The return lines on the Mags are a tad bit smaller so I would guess that they are 3/4" in diameter.

 

[dnjan]

Just to clarify - is it 1" pipe? or does the outside diameter appear to be about 1"? Also, what kind of flex line is it? Clear? Spaflex? Something else?

 

[griffinrl]

Well it's clear flex hose on the overflows to the sump. And it appears to be 1" ID. The flex hose going from the pumps is smaller and is black and flexible. Sort of like a rubber type hose.

 

[dnjan]

OK.

I would use 1"pipe from the Mag12 until you split it for the two returns.
And I would run the overflows separately into the sump.

If you use flex hose, the only flex hose I would use is spa-flex. It holds it's diameter and doesn't easily get pinched off.

 

[griffinrl]

Thank you for all the help Don. I'm new at this and I'd really like to get the thing plumbed correctly the first time. Especially if I can reserve the Mag 7 to drive a decent skimmer. I'll see if my local Home stores have Spa Flex. Is it known by any other name?

 

[dnjan]

I have only called it spaflex. It is the white flexible tubing used for plumbing whirlpool baths, etc. The spaflax, because it is flexible, doesn't transmit vibrations as much as rigid tubing. It is definitely more expensive than rigid PVC, but can be quite effective for gradual bends instead of sharp right angles with respect to reducing headloss in aquarium plumbing systems.
At a minimum, I prefer to use at least a short length between a pump and rigid tubing just to make things quieter.

If you are new to aquarium plumbing, you might want to also consider installing true unions before pumps. It makes it easier to remove a pump for cleaning, etc.

 

[griffinrl]

I'm new to plumbing in general. We had some additions to our home and I have a ton of PVC laying around. I had proposed to run a hard straight drop from the overflows into the sump with a 90 to the sump and a 90 down on both. The return from the pump would be the same basically. I've attached a simple diagram. My only concern was the elbows...I understand it impacts flow.

 

[dnjan]

I would use 1" return line as much as possible, and just reduce to 3/4" where it enters the tank. I would also use an overflow line larger than 1".

Before you glue-up the plumbing, decide what you are doing in your sump.
Will there be a lighted section with macro-algae? You might want to have one of the overflows go directly into that section.
In another thread you mentioned the possibility of having gravity flow into a skimmer. So run the other overflow in to that.
You will want separate, baffled parts in your sump so that you have a section with relatively level surface conditions to use as a control for your automatic topoff. I use the section in my sump that the return pump inlet is in.

And remember, true unions are you friends! Anything assembled may need to be disassembled, and true unions are better than a hacksaw.
For sure, put a true union immediately after every pump.

 

[griffinrl]

So I should run 1" line to both return bulkheads? The current fittings are approximately 3/4" according to my calipers. Would I put a 1" to 3/4" reducer right at the bulkhead? And again my return hoses are 1" in diameter. I assume I can get a fitting that will attatch to the 1" fitting to increase it to what? 1.5"? I apologize for all the tedious questions but I want to set it up as correctly as possible while it's empty and I can take my time.

 

[dnjan]

Run oversize plumbing as much as possible. In your case, that means right up until you put in the adapter to reduce the size.
You would be amazed how much stuff accumulates inside of pipes in a tank. After a few years I had an eighth-inch buildup on the inside of the original return line I had installed. In addition to reducing the inside diameter, the buildup is significantly rougher, and will have a serious effect on flow. So I replaced my return line with a size larger, and restored the original flow that I started with.

Be careful in estimating fitting size with a calipers. Pipe sizes are kind of screwey. Go to home depot, and look at their PVC fittings. Figure out what nominal pipe size you need to match the bulkhead in your tank.

The fittings are cheap - you might want to buy a 1/2", a 3/4" and a 1" fitting just to have around for comparison.

As far as changing diameter, that is easy. They sell a whole assortment of reducing unions and bushings. Just cruise the PVC fittings section of Home Depot or Lowes.

 

[griffinrl]

Thank you Don. I'll swing by the local Lowe's and see what they have. I have plenty of Sch 40 1" and 3/4" pvc in the shop to mess around with. I do plan on using the correct valves and unions in the system so I'll see what I have local. I appreciate all your patience.

 

[krisfal]

In case it hasn't been mention the Mag pump produce a lot of heat and unless you are planning a chiller having 2 of them in a small sump will probably cause issues. I recently tried running a becket style skimmer with a mag 12, in addition to my mag 24 return and it heated the tank by 1.5 degrees in less than an hour. I ended up going with a different plan for a skimmer.

 

[griffinrl]

Right now my main issue is just using the single Mag 12. I have a 29 gallon sump and I plan on upgrading to at least a 55 when I find a good local deal. I'd just like to run the returns to both overflows with one pump. I'm making rocks for the tank as we speak...and while they are freshwater curing I wanted to get the plumbing right. I'll eventually switch out the 12 for a larger one but I think in the meantime it should be fine for a 185 lightly stocked.