Split Sump Configuration

[Tobin VP]

I have limited sump space and want to expand my current Red Sea Reefer 2000XL to accommodate the new ReefMat and add a refugium. I'm planning to add another sump outside my cabinet thus creating a split sump. The idea would be to bridge these two sump compartments together with a large bulkhead. I'm planning to have the display tank drain to the first (exterior) sump where I will have a ReefMat and refugium. Then this sump will connect to the second sump beneath the cabinet where I will have my protein skimmer, probes, dose lines, and return chamber. I'm planning to use a single 1.5" diameter bulkhead and union to connect the two sumps below the target waterline. Does anyone have experience doing this? Any lessons learned here? Any additional considerations other being sure that my connection diameter is sized to my flow rate?

The only thing I'm also considering is putting in two bulkheads - the primary one would carry flow and then a second one above the water line would be in place in the event of any blockage or backup in the primary connection. Does this seem like overkill or worth the additional glass cutting and expense?

Thanks in advance for any opinions on this.

 

[ReefStable]

I've thought about doing this at one point too. I highly suggest second drain if you do go down this path. Just in case of a blockage like you mentioned.

 

[magallonbuckinbulls]

That will work brother. Definitely have the (2) 1.5" bulkheads setup as described (sized properly per pump demand). Redundancy is the key.
Make sure you don't have a rigid connection between the bulkheads to prevent damage to the sumps.

 

[Tobin VP]

That will work brother. Definitely have the (2) 1.5" bulkheads setup as described (sized properly per pump demand). Redundancy is the key.
Make sure you don't have a rigid connection between the bulkheads to prevent damage to the sumps.

I have also thought about the rigidity issue, but since both sumps are weighted by their water I wasn't too worried about it. In general this would be another great safety precaution if a sump got bumped and transferred a load to the bulkhead. BUT - my issue is I don't have much space as I want the sumps very close to one another.

What type of flex connectors do you suggest?

I assume two nipples with stainless steel rings and braided PVC tubing? This would push the two sumps at least 4-5" apart to accomplish in a straight shot. I possibly could put in 90 deg bends and accomplish putting sumps closer tougher with offsets. Is all of this worth it?

 

[magallonbuckinbulls]

I would use something like this. An isolation coupling. Look up the core t specs you need and I would use the pvc clamps, not SS hose clamps. You can find those online too.

 

[exnisstech]

I have no experience with this but I read about a similar set up from one of the manufacturers, maybe redsea? The problem the person had was not enough flow through the bulkhead to the second sump. Like I said just something I read and may very well have been user error just figured I'd mention it.

 

[Jamie814]

I've got mine setup with 3 separate tanks, 2 refugium's with rock, Fiji and miracle mud with a central sump under my 500 gallon. All tied together with four 1.5" bulkheads. Display drains into through back of sump into filter sock chamber then down under baffel into skimmer then out through 1.5" bulkheads on each side with pvc under the rock to outside ends of refugium's flowing back towards the sump into 1.5" bulkheads on each side of the return pump chamber where return pumps sit in sump. Never had any issues. They do all sit on 3" of styro and there are gaskets sandwiched on the bulkheads between the 3 tanks as well. In all these 3 tanks are about 130" long side by side.

 

[Tobin VP]

I would use something like this. An isolation coupling. Look up the core t specs you need and I would use the pvc clamps, not SS hose clamps. You can find those online too.

I like the mount of flex there. I was only able to find these.

Can you send an online link to this product? Also, are you referring to PVC plastic clamps with ratcheting teeth that BRS sells? Are you suggesting this to keep metals away from salt environment?

 

[Tobin VP]

I have no experience with this but I read about a similar set up from one of the manufacturers, maybe redsea? The problem the person had was not enough flow through the bulkhead to the second sump. Like I said just something I read and may very well have been user error just figured I'd mention it.

Thanks for heads up on this. Yes RedSea uses them in their new big tanks. It does not appear that they put in isolation couplings but they have two connections fairly separated and likely it would help prevent any hinging stresses.

You do have to be careful of sizing the connection. I have computed major/minor head losses (standard civil engineering equations for wastewater scenarios). For a max return pump turn over of 750 gph with a connection of 1.5" diameter and 4" in length, the head loss is 1.6". So the first reservoir will maintain a water level 1.6" higher at 750 gph of flow through sumps.

I've also used orifice equations to look at blockage (possibly algae build up or snail) ... this is what has led me to wanting to put in an additional connection. The head loss starts going up quickly for blockages and I want a safety spillway in place for any such situation.

 

[Tobin VP]

I've got mine setup with 3 separate tanks, 2 refugium's with rock, Fiji and miracle mud with a central sump under my 500 gallon. All tied together with four 1.5" bulkheads. Display drains into through back of sump into filter sock chamber then down under baffel into skimmer then out through 1.5" bulkheads on each side with pvc under the rock to outside ends of refugium's flowing back towards the sump into 1.5" bulkheads on each side of the return pump chamber where return pumps sit in sump. Never had any issues. They do all sit on 3" of styro and there are gaskets sandwiched on the bulkheads between the 3 tanks as well. In all these 3 tanks are about 130" long side by side.

Great setup! Beautiful sump room.

Out of curiosity. What is your approximate return pump flow rate? And what is the difference in water level between your center sump and the outside sumps? (From photo it looked like about 1-1.5" of head loss)

I want to do a quick check to be sure that my modeling assumptions are correct for the equations that I'm using.

 

[Tobin VP]

I've got mine setup with 3 separate tanks, 2 refugium's with rock, Fiji and miracle mud with a central sump under my 500 gallon. All tied together with four 1.5" bulkheads. Display drains into through back of sump into filter sock chamber then down under baffel into skimmer then out through 1.5" bulkheads on each side with pvc under the rock to outside ends of refugium's flowing back towards the sump into 1.5" bulkheads on each side of the return pump chamber where return pumps sit in sump. Never had any issues. They do all sit on 3" of styro and there are gaskets sandwiched on the bulkheads between the 3 tanks as well. In all these 3 tanks are about 130" long side by side.

Those sumps look very close together. Did you use a single bulkhead through both sump walls with a double gasket. One gasket on each tank wall?

 

[Jamie814]

Great setup! Beautiful sump room.

Out of curiosity. What is your approximate return pump flow rate? And what is the difference in water level between your center sump and the outside sumps? (From photo it looked like about 1-1.5" of head loss)

Thanks!
I'm not sure on the actual flow rate, I run two cor20 pumps at about 50%
Just measured water levels for you
Skimmer section has 9" water level (controlled by gravity feed ATO float valve)
Refugium's sit at a 7.5" water level after two 1.5" bulkheads and about 4' of pvc on each side.
Return chamber has a 6.75" water level after two 1.5" bulkheads with a 12" long 1.5" suction screen on each.

Those sumps look very close together. Did you use a single bulkhead through both sump walls with a double gasket. One gasket on each tank wall?

Single bulkhead with 2 gaskets, one on the flange (head) side and one sandwiched between the two tanks, no gasket on the nut. This is the same way external overflow box bulkheads are installed.

Here's the other side of the room.

 

[BeanAnimal]

I wouldn't worry too much about stress or flexible fittings. Just get things lined up well. Trying to get a flexible coupler in a small space is going to be terrible.

If you are afraind of alignment, then use uniseals

They will allow you to connect the sumps together with a single pipe, even if at slight angles and will remain "flexible" if if there is movement. I would use a single 2" pipe or (2) 1.5" pipes. Either will give you roughly the same area.

 

[Tobin VP]

Thanks!
I'm not sure on the actual flow rate, I run two cor20 pumps at about 50%
Just measured water levels for you
Skimmer section has 9" water level (controlled by gravity feed ATO float valve)
Refugium's sit at a 7.5" water level after two 1.5" bulkheads and about 4' of pvc on each side.
Return chamber has a 6.75" water level after two 1.5" bulkheads with a 12" long 1.5" suction screen on each.

Thanks for sharing this info. I calculated flow rate from the head loss you see between skimmer section and refugium. With 4' of 1.5" pipe and an 1.5" head loss between the two chambers ... and considering both minor and friction losses you would be getting 500 gph of flow. This of course is per pump. If you figure about 8' of head loss for each pump (5' of vertical plus two 45s and a 90 bend) the COR 20 predicts about 1000 gph. You said you were running each pump at 50% so this checks out nicely.

Checking between the refugium and the return pump chambers was harder since I could not make out the exact plumbing in the image. Looks like about 12" of PVC with 2 90 deg bends and then the 12" screen? If I just assume an equivalent 6" of PVC with 0.75" of head loss I get about the same 500 gph flow rate per pump.

It looks like you're getting about 1000 gph total of return flow into your system.

Thanks for sharing info - it has been a good check that my modeling assumptions are accurate enough to continue with my design.

 

[Tobin VP]

Here's the other side of the room.

Very jealous of your setup. It's like a museum presentation of sump rooms !!!

Now you are obliged to show us a pic of the display as well !!!

 

[Tobin VP]

I wouldn't worry too much about stress or flexible fittings. Just get things lined up well. Trying to get a flexible coupler in a small space is going to be terrible.

If you are afraind of alignment, then use uniseals

They will allow you to connect the sumps together with a single pipe, even if at slight angles and will remain "flexible" if if there is movement. I would use a single 2" pipe or (2) 1.5" pipes. Either will give you roughly the same area.

I have to admit ... every time I have ever looked at these uniseals I have cringed ... assuming that they are not very heavy-duty and very leak prone. But sounds like I need to use them myself before judging. After spending a great deal of time in 2010 studying your Beananimal Overflow design ... and then building a mockup to test it's performance ... I have to say I gained a great deal of respect! Really brilliant work. As a result I will stay a lot more open minded to uniseals now going forward

For my system I'm really not that worried about alignment. I think I can layout the sumps accurate enough. Another poster suggested it and under other circumstances I like the approach of playing it safe and agree ... but always have hated the additional connection points/clamps/etc. With my space constraints I think I will use schedule 80 rigid bulkheads, layout carefully, and (of course) implement leak detection sensors on floor!

 

[Tobin VP]

For those curious about sizing bulkheads for split sump setups be advised that bigger is obviously better/safer. But of course it's always a tradeoff, bigger is more expensive (bulkheads, hole saws, etc) as well as the space considerations.

Ultimately, it depends on the size of your system and the resulting return pump turnover you are targeting. Since head loss goes up as the square of the flow rate (through the bulkhead) you can get some pretty large differences between chamber water levels resulting in potentially overflowing the sump!! Moreover depending on protein skimmers, filter rollers, etc you may want to be targeting a range of water levels in each chamber.

I'm computing frictional head loss (using Manning's Equation) plus minor head losses (in my case just entry and exit losses of bulkhead). As the above real world example shows this produces a very reasonable prediction. Below are some head loss calcs (chamber height difference) for general reference. Each assumes a system targeting 10X return pump turn over (as a max) and a single bulkhead:

1" Diameter Bulkheads (3.5" length)
300 gph (30 gal system) -> 1.4" difference
400 gph (40 gal system) -> 2.5" difference
500 gph (50 gal system) -> 3.9" difference

1.5" Diameter Bulkheads (3.75" length)
500 gph (50 gal system) -> 0.7" difference
750 gph (75 gal system) -> 1.6" difference
1000 gph (100 gal system) -> 2.8" difference

2" Diameter Bulkheads (4" length)
1000 gph (100 gal system) -> 0.87" difference
1500 gph (150 gal system) -> 2.0" difference
2000 gph (200 gal system) -> 3.5" difference