Calling all math geeks

[Miller535]

I appreciate your help! I should have looked at the PVC requirements more. What about a submersible return pump, rated for 1200 gph? I know you have to account for head loss and pressure loss through fittings, and then calculate psi. Even if it was plumbed in with schedule 40 it wouldn’t exceed that limit?

You are definitely over thinking this. Lets say you want to build a 100 gallon tank. Then choose a overflow that supports the turnover you want, (5-10% of tank volume). Then figure out the distance from the tank to sump. There are very basic head loss calculators out there. No need to figure out psi, and all of that other stuff.

 

[Strawberry]

You are definitely over thinking this. Lets say you want to build a 100 gallon tank. Then choose a overflow that supports the turnover you want, (5-10% of tank volume). Then figure out the distance from the tank to sump. There are very basic head loss calculators out there. No need to figure out psi, and all of that other stuff.

That’s all I was trying to do homie I don’t know where it all went wrong lol. I was just trying to make sure the overflow supported 6 turnovers which is like 450 gallons so I wanted to double check and ask what others thought.

 

[Vakko]

My tank is at 75x turnover. Imagine trying to do that with just a return pump...

 

[Strawberry]

My tank is at 75x turnover. Imagine trying to do that with just a return pump...

It would be easy if it was a small tank. lol but I said that I was not aiming to get that turn over only from my return pump in earlier comments. I just learned today the difference between sump turn over and tank turn over.

 

[Brew12]

Thanks for the chart. I did do my calculations using schedule 80 which could be partly responsible for some of the flow rates being off. I was trying to apply the principle of overall water pressure from the system (using gravity, SG of water, and vertical dimension from water level). To see how that would affect it. For example, a 5 gallon water jug fills a cup faster when it is full than it does when it is nearly empty. The holes in this design being on the bottom should be more efficient than your typical tank drilled on the side. Not sure where I went wrong here lol

I think your calculations are off because you did not take into account the drop in the piping. Your total head is from the top of the water in the tank to the bottom of the pipe where the water discharges.
I'd recommend using the chart provided to get your flow rates. If it were my system I would use 1" bulkheads as they are pretty standard. I would consider 3/4" bulkheads if cosmetics were important. You may find the 3/4" piping to be more compatible with the return pumps you would want to use.

 

[Strawberry]

I think your calculations are off because you did not take into account the drop in the piping. Your total head is from the top of the water in the tank to the bottom of the pipe where the water discharges.
I'd recommend using the chart provided to get your flow rates. If it were my system I would use 1" bulkheads as they are pretty standard. I would consider 3/4" bulkheads if cosmetics were important. You may find the 3/4" piping to be more compatible with the return pumps you would want to use.

Those are the values that I used, but it was for schedule 80 PVC so maybe that has something to do with it. I see now that it was overkill to solve for those flow rates, but it never hurts to challenge yourself every now and then! Haha, putting that good old practical algebra to use. And I used to think I’d never use it

 

[Brew12]

Those are the values that I used, but it was for schedule 80 PVC so maybe that has something to do with it. I see now that it was overkill to solve for those flow rates, but it never hurts to challenge yourself every now and then! Haha, putting that good old practical algebra to use. And I used to think I’d never use it

I did the math on mine just because I wanted to. And you are right, it is way overkill! The math needed for all of the 90 degree fittings and trying to actually figure out the water drop... not worth it! I came pretty close to the chart when I used a 1M water height. Not sure why yours are off. Schedule 80 shouldn't make that much of a difference.
But, what really makes it not worthwhile is that the biological growth you get on the inside will restrict flow much more than the difference between schedule 80 and schedule 40. And, there is no way to calculate it accurately imo. Now I tell everyone to use a chart and make sure they oversize it accordingly.
For what it is worth, pump head calculations are much easier than the drain calculations!

 

[Strawberry]

I did the math on mine just because I wanted to. And you are right, it is way overkill! The math needed for all of the 90 degree fittings and trying to actually figure out the water drop... not worth it! I came pretty close to the chart when I used a 1M water height. Not sure why yours are off. Schedule 80 shouldn't make that much of a difference.
But, what really makes it not worthwhile is that the biological growth you get on the inside will restrict flow much more than the difference between schedule 80 and schedule 40. And, there is no way to calculate it accurately imo. Now I tell everyone to use a chart and make sure they oversize it accordingly.
For what it is worth, pump head calculations are much easier than the drain calculations!

I took a fluid power class and learned tons of equations for pressure changes, pump size calculations, and even using the K-factor of fittings to see how much they would restrict flow! I love stuff like that. I’ll probably rework it just because I have to convince my wife, who is also skilled trades and NOT a reef hobbyist, that I know what I’m doing (or at least make it look that way) lol.

 

[Vakko]

Best way to get wife involved is to ask her about your thoughts. But simple thoughts like:
what do you think of this fish?
what do you think of this coral?
could you help me out real quick? I was trying to figure out if I should use schedule 40 or schedule 80...

Of course, it can always backfire if you kill her favorite fish...

 

[Strawberry]

Best way to get wife involved is to ask her about your thoughts. But simple thoughts like:
what do you think of this fish?
what do you think of this coral?
could you help me out real quick? I was trying to figure out if I should use schedule 40 or schedule 80...

Of course, it can always backfire if you kill her favorite fish...

Hahaha I’ll try that! She actually named my pistol shrimp because he’s a jerk and she loves his snappy attitude. Lol his name is Gunner.