Dual Herbie on 180G, what size drains should I use?

[PedroYoung]

I have a dual corner overflow, with a pair of 1" bulkheads in each overflow. I'm using an Abyzz A200 for return from my basement sump. My plan is to have relatively low turnover, 5ish X my 210G system volume. I read on GMAC reefs writeup on dual corner overflows that because of the capacity of full siphon drains the valves would be turned way down and might be finicky. Should I consider using 3/4" for the main siphon drain, then 1" for the backups? My return are going to be outside the overflow box (either over the back or bulkhead through the back). Anyone with experience who could comment would be greatly appreciated.

 

[Brew12]

I have a dual corner overflow, with a pair of 1" bulkheads in each overflow. I'm using an Abyzz A200 for return from my basement sump. My plan is to have relatively low turnover, 5ish X my 210G system volume. I read on GMAC reefs writeup on dual corner overflows that because of the capacity of full siphon drains the valves would be turned way down and might be finicky. Should I consider using 3/4" for the main siphon drain, then 1" for the backups? My return are going to be outside the overflow box (either over the back or bulkhead through the back). Anyone with experience who could comment would be greatly appreciated.

I would plumb them at 1" with a gate valve. Yes, the valves do get a little touchy at low flows but it won't be much of a difference between 1" and 3/4". If you do keep the 500gph+ on both drains the 1" valve should control fine.

I have a dual corner overflow 120g and if I were going to keep the system I would re-plumb it as a bean animal. I would put the full syphon and emergency in one corner with the partial drain and return in the other. This way I would have flow in both corners with a more stable setup and a more hidden return. Again, I don't have experience with this, only something I've toyed with the idea on.

 

[ca1ore]

Honestly, if the tank is empty do yourself a favor and rip out the corner flows, patch the bottom holes and drill for a ghost-style overflow. I just switched from a dual corner ML265 to a custom ghost overflow and MAN, what an improvement. I tried all combinations/permutations with my old tank and they all sucked.