Flow questions for future 265 build

[Newbie012000]

Hello everyone. I have previous experience with fish only tanks and poor unsuccessful prior experience with reef tanks due to lack of patience when things become frustrating and no quarantine practices and life in general. Therefore, I am new to this hobby, but have decided to get back into the hobby and take my time and do everything properly this go around.

 

I have acquired a new Marineland 265 gallon tank with two overflows on both sides of the rear of the tank. There are two holes in each overflow that all measure 1”, for a total for 4 1” holes.

 

When I set up the tank (April/May this year), I plan to use pukani dry rock (cooked for two months)

 

Based upon the research I have done, I need a return pump to pump approx 5x to 10x gph flow/turnover through the tank. I also read that a 1” hole/drain will allow approx 600 gph of water to drain via gravity and that a 1” return line can handle on avg 2220 gph.

 

Would there be any problems with me using three of the holes as drain lines allowing approx 1800 (approx 6 X turn over) or should I use all 4 as drains to allow 2400 gph through the drain lines?

 

Also, would one 1” return be sufficient for this build? My research say that a 1” return can handle an avg 2200 on the return (so perhaps I would have to throttle back some of the drain lines) so that The sump would not be overwhelmed by 2400 gph rate through the drains. Hope this makes sense.

 

I was planning to have a 1” return line split into a T and then have two one inche returns feed into the tank.

 

Please share your thoughts. I hope this was written clearly enough

[Origami]

Don't get hung up on sump turnover if it's going to cause a headach. I would put your minimum sump turnover at 0.75x as the real floor.

 

Personally, I'd have at least two returns if you have two drains. This ensures that the water coming up from the sump is more evenly distributed. I also like the extra redundancy of a second return. Doubling up on the return also reduces the flow (rate) through the pipe. Thus, you'll lose less to friction and improve power efficiency (and operating costs). 

 

To reduce dynamic losses due to friction between the fluid and the pipe, use plumbing larger than 1-inch under the tank (especially on the pressure returns). Size the plumbing there with at least 1-1/2 and preferably 1-1/2 pipe if you have any longer runs. If you split into two one inch lines, then you'll want to common line sized at 1.5" at least.

[Newbie012000]

Wow. Thx for the response. I am surprised that you referenced 0.75x as the floor for turnover.

For clarification, As far as the pipes for the drain lines, since the holes are only one inch, will there be any benefit to utilizing 1-1/2 pvc for the drain lines? I’m straight with your advice on the return lines.

[Origami]

Wow. Thx for the response. I am surprised that you referenced 0.75x as the floor for turnover.

For clarification, As far as the pipes for the drain lines, since the holes are only one inch, will there be any benefit to utilizing 1-1/2 pvc for the drain lines? I’m straight with your advice on the return lines.

Yeah. Conventional wisdom put sump turnover at 5-10. However, I'm basing the 75% figure on the an old rule of thumb that said that 75% of your water volume should move through your skimmer in an hour. You simply can't do that if any less water is flowing through the sump. You'll want to increase this number a little if your tank loses so much heat that the tank can't reach your target temperature, but I'm figuring that's not going to be a huge problem. 

 

The bottom line is not to lose a lot of sleep over sump turnover. It's an old figure that's much like the old Watts per gallon guideline that we used to use to estimate lighting needs. 

 

Instead, focus on energy efficiency and reliability/redundancy and expandability to include more automation as you grow into the hobby.

[zygote2k]

In-tank circulation is more important than flow through the sump. You could easily take 3 of those holes and use them for drains and have one as the return.

[Newbie012000]

Thx guys for the info and advice. Definitely helps me plan this build.

[Shoelace]

In-tank circulation is more important than flow through the sump. You could easily take 3 of those holes and use them for drains and have one as the return.

 

I definitely agree.  I have an "old-school" durso two overflow 180 and I set the 4 holes up as emergency dry overflow, return, wet overflow, siphon.  It's very quiet.  Most of flow is in tank.