Overflow box hang on back sizing - EShopps

[djmincer]

Hello!
I've got a few questions but mainly about overflow box size. I'm setting up a 125g tank. I am trying to decide on which EShopps hob overflow size to get. I have two DC return pumps in my sump, the Jebao MDP-6000 (1637GPH) and the Jebao DCW-6000 Sine (1600GPH). One will run straight back up to the tank and the other will run through a 25w UV sterilizer on the way back up to the tank. 125g is the dividing line between the Eshopps PF-800 (800GPH flow) and PF-1000 (1000GPH flow). Which should I get?

Also, the PF-1000 has two drains, which I guess means I'd have two separate drain lines into my sump. I have a Reefmat 500 in the sump that the water coming from the tank should flow through first, but if I have two drain lines, how does that work? Should I have the two drain lines connect into one on the way down to the sump? Wouldn't that slow down the flow making the second drain from the overflow box pointless?

 

[Lou City Reefing]

I'm sure others have better information and solid concrete evidence to support their claims, but I would suggest the larger of the two overflows so you could have more headroom to increase the flow from your return pump(s) if needed in the future.

By two drains I would assume you're talking about have 1 main and 1 emergency drain. I don't think it would be advisable to connect those two drains together. You should have full suction of water going down your main drain and the emergency should be dry, or some people do a *SMALL* trickle of water down the emergency line. The emergency drain is incase your main drain gets clogged for whatever reason.

 

[djmincer]

I'm sure others have better information and solid concrete evidence to support their claims, but I would suggest the larger of the two overflows so you could have more headroom to increase the flow from your return pump(s) if needed in the future.

By two drains I would assume you're talking about have 1 main and 1 emergency drain. I don't think it would be advisable to connect those two drains together. You should have full suction of water going down your main drain and the emergency should be dry, or some people do a *SMALL* trickle of water down the emergency line. The emergency drain is incase your main drain gets clogged for whatever reason.

That makes perfect sense to me. I've read that the second drain is indeed an emergency drain in case the main becomes clogged, so you are right on. I'm wondering water doesn't just flow down both drains simultaneously. Must be that the emergency drain sits a little bit higher or something. Thank you for responding!

 

[exnisstech]

I ran two pf800s, one in each corner on 6ft 180g for 6 years. I ran my return over the top in the center with a y and two nozzles.

 

[Asm481]

Been a couple years for me but I did a 125 with a single overflow in the center. When I was at your point I was concerned with the fact that you need to maximize the flow through the u-tubes from the display to the drain portion. I was running a basement sump so two returns was not a consideration. I would probably go with the smaller overflow box, your uv light might not be run at all times and usually at a slow flow especially with a smaller wattage like you have going.

 

[djmincer]

I ran two pf800s, one in each corner on 6ft 180g for 6 years. I ran my return over the top in the center with a y and two nozzles.

That's a beautiful tank! I love the flow and am looking forward to adding corals after I get my parameters established and stable.

 

[djmincer]

Been a couple years for me but I did a 125 with a single overflow in the center. When I was at your point I was concerned with the fact that you need to maximize the flow through the u-tubes from the display to the drain portion. I was running a basement sump so two returns was not a consideration. I would probably go with the smaller overflow box, your uv light might not be run at all times and usually at a slow flow especially with a smaller wattage like you have going.

Does water flow down both drains all the time and if not, what keeps it only going down one drain while the other is the "emergency backup drain"?