drain capacity
- Thread starter tor101898
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prop-frags
SPS Slave
Several factors play into the (theoretical) answer.
1) linear width of the overflows
2) weirs and their width
3) drain size and type
4) thickness of water flowing over the overflow
I haven't seen any real world test results of the stock 250DD or 300DD drains. But just playing around with the calculator and making assumptions of the stock 300DD, about 1000 GPH is the best you could do assuming the linear overflow size is 15" (7.5" x 2). This would also assume two 1" drains... The limiting factor are the overflows though, and you'd probably need to modify those weirs to actually get that much flow across them.
1) linear width of the overflows
2) weirs and their width
3) drain size and type
4) thickness of water flowing over the overflow
I haven't seen any real world test results of the stock 250DD or 300DD drains. But just playing around with the calculator and making assumptions of the stock 300DD, about 1000 GPH is the best you could do assuming the linear overflow size is 15" (7.5" x 2). This would also assume two 1" drains... The limiting factor are the overflows though, and you'd probably need to modify those weirs to actually get that much flow across them.
Alex T.
Active member
I agree with prop-frags. I think it's unfortunate that Marineland or any other "reef ready" tank doesn't come equipped with a minimum of (2) 1 1/2" drains. The one inch drain is handicapped at what it can truly pull. Without siphon, you'll never get over 800 abysmal gph draining to your sump. Depending on a siphon every time is a recipe for disaster if your pump is too strong.
Any true reeftank manufacturer should eliminate all 1 inch holes for drains and give us reefers the 1 1/2" drains as standard, with a 2" drain upgrade option. A 2 inch drain can easily pull 2,000 gph without siphon. Two of them and you could comfortably return 4,000 gph back to the tank. That almost eliminates needing two powerheads. It's a shame. Any tank manufacturers out there listening?
Any true reeftank manufacturer should eliminate all 1 inch holes for drains and give us reefers the 1 1/2" drains as standard, with a 2" drain upgrade option. A 2 inch drain can easily pull 2,000 gph without siphon. Two of them and you could comfortably return 4,000 gph back to the tank. That almost eliminates needing two powerheads. It's a shame. Any tank manufacturers out there listening?
prop-frags
SPS Slave
Since today is Pi Day, and we're talking about drain capacity, I thought I would post a few useful reference tools for calculating drain capacity:
Pipe Equations
Schedule 40 PVC Pipe Friction Loss and Velocity Diagram
Calculating flow of water through pipes
PVC Pipe Flow Chart
Pipe Equations
Schedule 40 PVC Pipe Friction Loss and Velocity Diagram
Calculating flow of water through pipes
PVC Pipe Flow Chart
mm949
New member
i use all the bulkheads in the overflow into 1.5" drain pipe(x2),each overflow has the potential of 1200-1500gph w/ 1.5" drain pipe...if the pump is under the stand, the reeflo dart has the max flow this set-up can handle w/o restriction, running 1.5" return feed up the back of the tank to the top
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