Overflow questions

[CindyKz]

Good morning R2R,

I need to order an overflow for a 180gal build. I was leaning toward Reef Savvy's Ghost but after reading multiple positive reviews of Modular Marine's boxes I am leaning toward MM. One thing I like is that they offer multiple sizes.

My question is, is it better to oversize the overflow a bit or stay with the recommended size? I'm on the fence between the 18 and 21". I plan to plumb it bean animal style.

TIA,

Cindy

 

[timnem70]

Wish I would've purchased a ghost overflow box for my tanks. Both are not drilled (that would have been best IMO) so I had to do an overflow with a siphon tube. If you have to go that same route, get one with this feature. That way if the power goes out and restarts, your not having to worry about the broken siphon as the pump keeps it continuous. It has worked flawlessly for the year I have had it.
Thanks and best of luck

 

[psturg66]

Sometimes it's better to have more and not need it than less and need it. I would probably go a little bigger to handle possible future upgrades.

 

[CindyKz]

Wish I would've purchased a ghost overflow box for my tanks. Both are not drilled (that would have been best IMO) so I had to do an overflow with a siphon tube. If you have to go that same route, get one with this feature. That way if the power goes out and restarts, your not having to worry about the broken siphon as the pump keeps it continuous. It has worked flawlessly for the year I have had it.
Thanks and best of luck

Thanks! I will be drilling though.

Sometimes it's better to have more and not need it than less and need it. I would probably go a little bigger to handle possible future upgrades.

That's my usual way of thinking! But unsure if having too much will be problematic. If I understand the plumbing correctly, I can dial back the flow to what I want with a gate valve anyway. Is this correct?

 

[psturg66]

That is also my understanding.

 

[malacoda]

The recommended sizes are more than adequate. They're designed to handle more than enough flow for the given tank size.

The 18" is rated for 1800ghp. That would be 10-times turnover from tank to sump on your 180g. General consensus is that 5-8 times DT-to-sump turnover is more than adequate for typical systems since it is only for filtration (now that in-tank powerheads provide the flow for the system).

Unless you plan on running an extreme amount of flow through your sump for some reason, going oversized with the 21" will only result in higher cost and more space being taken up by the internal skimmer box without gaining any real benefit return.

 

[CindyKz]

The recommended sizes are more than adequate. They're designed to handle more than enough flow for the given tank size.

The 18" is rated for 1800ghp. That would be 10-times turnover from tank to sump on your 180g. General consensus is that 5-8 times DT-to-sump turnover is more than adequate for typical systems since it is only for filtration (now that in-tank powerheads provide the flow for the system).

Unless you plan on running an extreme amount of flow through your sump for some reason, going oversized with the 21" will only result in higher cost and more space being taken up by the internal skimmer box without gaining any real benefit return.

That makes really good sense. I doubt I would go above 8x turnover anyway, which even being conservative gives some breathing room with the 18".

I started wondering if I should overshoot a little bit because while researching the Reef Synergy Shadow I noticed that the flow rates posted by the manufacturer were different than those posted on the BRS website. I wrote to BRS, here is the question and response:

Your Question: Hi BRS, Here in your product info you state a 1500 gal/hr flow rate for the 16" shadow, but the Reef Synergy website states 2500 gal/hr. Which is correct? I'm planning a 180 gal build so it is the difference between one or two overflows if I use the shadow.

Thanks much, Cindy

Answer: Great question Cindy,
We rate things more conservatively than the manufacturer, which is why there is a discrepancy in the estimated flow rate. I would recommend going for two for the extra redundancy and the ability to have more control over the tank turn-over.
Happy Reefing! ​

As you pointed out though, I will have breathing room even if the 18" doesn't quite live up to the manufacturer specs (and I have no reason to believe it won't).

Thank you for the valuable input

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