Overflow size question

[Hoggwild]

150 gallon (tall). Planned on 1800gph using 1.5 in. sched 80 bulkheads.
Any harm in using a 2400 gph overflow and using a the same bulkhead and pump to produce 1500-1800 gph?

 

[Julius Chen]

The larger overflow usually comes with longer weir, gives better surface skimming and less noise. It also lower water line tiny bit (with given return pump power), so if u are like me prefer waterline be hidden behind rim, u need to play with height of overflow box or increase your pump power a bit.

My tank is 120g (4'x2'x2'). 2400 gph ghost overflow is what i use. My return is 1" and main drain 1", the other two drains are 1.5". All schedule 40.


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[mcgyvr]

No harm in using an overflow rated for higher than your are pumping..
Thats how it should be done..

 

[thegrun]

The larger overflow box is fine, but I would strongly recommend using 1" PVC for your primary drain line rather than 1-1/2" or even 1-1/4". A 1" drain line with 3' of drop will handle a little over 2000gph at full siphon, certainly more than the 1800 gph you are designing to. If you use a 1-1/2" drain line it will be very difficult to make the fine tuning you need to make your drain line perfectly silent due to the fact that the slightest movement of the 1-1/2" gate valve makes a big change to the flow rate. Use 1-1/2 as the emergency drain(s), but 1" as the primary drain line size, you will thank me after you have the system up and running!