how much water will drain though a 1 1/2inch hole

forgot to mention, u should do this with the water in the tank at the level it will be run at. i think flow would vary with changing height of water above the orifice.

 

This is correct. Just like a 12.5 inch telescope mirror gathers 2.5 times the light gathering power of an 8 inch. Imagine a 1.5" circle on top of the 1" circle.

 

On my 193g plywood tank, I almost put two 1.5" bulkheads int he overflow for drains.

I ended up doing two 1" because IMO, there is no need for that much gph going into a sump. I will add flow with pumps to the display. My return pump is 780gph. The same return pump on my 90g RR with one 1" drain works fine, so the second is more redundancy than anything. I might make 1 durso higher than the other by a little bit.

I can always add another bulkhead by draining the couple gallons from the overflow, and drilling another hole or 5 in the overflow box bottom. Simple enough, but I really doubt I will need to.

 

More than you want to clean up!!!

Sorry, that wasn't constructive at all

 

I went with 2x 1.5" bulkheads on my 160g plywood tank because if a snail ever got stuck in one (or heaven forbid a fish), then i want my other bulkhead to be able to handle all the flow from my pump. At any rate, you have to look at flow rate volume. Those guys have it right. The flow rates grow exponentially larger in relation to the diameter.

 

ok thanks everyone....

 

For clarity's sake, it is important to note that flow through a pipe is roughly proportional to the pipes cross sectional area not the diameter of the pipe. The area of a circle (pipe) is detrmined by (pi)(r)sq or (3.14) times the radius times the radius. When it comes to plumbing fish tanks this principle is very important to remember when you are considering going with a smaller size pipe. In other words... "maybe I'll save some money with 1" pipe instead of 1.5" it will only cut my flow by a third" can lead you to a nasty suprise. There are a lot of other factors that will affect the flow rate through your pipe (wall thickness of the pipe, length of the pipe, number and type of fittings, pressure on the liquid, head pressure, etc...). For those who would like a handy reference check out GPM/GPH Flow based on PVC Pipe Size, ie, How much water can flow through Sch 40 Pvc Pipe Size 1/2" 3/4" 1" 1.5" 2" 2.5" 3" 4" 6"
You can see that for Sch 40 flowing by gravity, 1" pipe will move 960gph and increasing to 1.5" more than doubles the flow to 2100gph.

 

There the chart is! Thanks gotosleep!


960 gph with sch40, per 1" pvc is more than adequate.but for those that want more flow, the increase from 1" to 1.5" does more than double the flow rating as I remembered.

 

yes thanks for the chart GoToSleep...