Do I need a valve on sump plumbing?????

[monocus]

i would probably go with a bigger drain.i'm using a stockman with a 2" drain

[sphelps]

Originally Posted by monocus

i would probably go with a bigger drain.i'm using a stockman with a 2" drain

I'm not sure how easy it would be to change out a 1" bulkhead to a 2" bulkhead, you would have to redrill the hole and even then there will not likely be enough clearance for a 2" bulkhead in the overflow box of a 50 gallon tank. a 1" drain will run up to 700 gph without an issue, and more than likely this is not the actual flow rate it will receive.

windcoast, what pump are you using or plan on using?

[lorenz0]

I have a gate on my drain, nothing on my emergency just it gets plugged. On the return I am running a check valve, which I reccomend. In 3 years I have not had anything overflow with this set up.

On my cube I had ball valves on the return and drain... no check valve. Now this set up I Had a spill once which fried a powerbar. everytime I did a water change I had to close the return line, there were a few times I almost forgot.

[Blom]

The flow though a gravity fed drainage line that discharges to atmospheric pressure can be roughly calculated using the continuity equation as it is a product of flow velocity and cross sectional area.

Q = A * V

Where Q is flow rate, A is cross sectional area of the pipe, and V is velocity.

The units work out this way:

M^3/sec = M^2 * M/Sec
OR
Ft^3/sec = Ft^2 * Ft/Sec

You can almost neglect head pressure as this will be offset by frictional losses in the pipe.

Remember you need to switch your time units from sec to minutes and convert to Gallons to get you gpm rate.

A good article for this can be found here:
http://www.agf.gov.bc.ca/resmgmt/pub...s/590304-5.pdf

Hope this helps.

[sphelps]

so what's the velocity?

[Blom]

Originally Posted by sphelps

so what's the velocity?

Well ideally you would measure this lol, but I dont see that being practical in this scenario. You could do this the way the pdf I posted goes about it, but this would be tough to find tables for as our elevation changes are small, or so I assume. Another way to do this would be to estimate the velocity based on gravitational acceleration:

9.81m/s^2
OR
32.2ft/s^2

Time how long it takes from the first overflow trickle till when its out of the piping. For example say it takes 2.5 sec to flow through, this would translate into a velocity of 24.5m/sec. This can give a ballpark figure. The more water volume on top of the intake though will create some head pressure, which then changes all of this. This assumes gravity fed drainage into atmospheric pressure.

Im sure if you google it someone has done the math!

[sphelps]

Yeah I was attempting to point out that equation isn't useful here, it's only for sizing pipe when you have a desired flow rate and velocity or solving for a different variable with the other two known. The velocity will actually depend on a few things including pressure difference, density (which is variable as well due to an inconsistent mixture of air and water), major loses from pipe friction and minor loses from pipe fittings. While it's completely possible to calculate this all it would be a complete waste of time especially since RC has been nice enough to make a simple calculator that estimates the required pipe size based on flow rate.
http://reefcentral.com/index.php/dra...flow-size-calc

[bignose]

You could also put a valve after the return pump to control flow rates if you don't want one on the drain.

[windcoast reefs]

Originally Posted by sphelps

I'm not sure how easy it would be to change out a 1" bulkhead to a 2" bulkhead, you would have to redrill the hole and even then there will not likely be enough clearance for a 2" bulkhead in the overflow box of a 50 gallon tank. a 1" drain will run up to 700 gph without an issue, and more than likely this is not the actual flow rate it will receive.

windcoast, what pump are you using or plan on using?

Hey! Im using a Hydor seltz pump (800 gph model). I calculated the loss in the gph from the head and it equals out to about 500 gph.

[windcoast reefs]

Originally Posted by monocus

i would probably go with a bigger drain.i'm using a stockman with a 2" drain

Thats pretty much impossible for me to do. I already have the largest bulkhead that I can get for the hole. And I can't drill it out anymore without affecting the structure of the tank.

I can maybe step up to a larger pipe ( 1 1/4" or 1 1/2"), but I don't know if it is a benifit considering the bulkhead restricts the flow.