Modular Marine Overflow -- Sizing Question

[BAPrince]

I'm spec'ing out my 170-180g build. It'll have a Tideline 48" sump (65g) for a total volume of 220g +/-. I will buying a Modular Marine overflow for the tank. The 1600gph model says it's rated for up to 175g tanks. At 3-5x turnover, I only calculate 525-875gph through the sump. That being said, I'm pushing up against the recommended limit of MM. If I go up to their 1800gph model, it upgrades from 1" drains (on the 1600) to 1 1/2" drains. Is there any disadvantage to having the larger diameter drain pipes/bulkheads? This is my first tank with a sump, so I really appreciate your collective expertise!

 

[ca1ore]

I'm a big fan of the MM overflows, but I tend to cut the max capacity in half as a better measure for practical sizing. On my 450, for example, I went with the 32" long 3,200 that I run at around 1,600 …. which seems about right to me. If I were you, I'd go with the 1,800 model …. longer skim box and bigger drains. Easy to choke a drain back; not so easy to make it bigger.

 

[BAPrince]

Thank you for the feedback @ca1ore ... since you have experience with the MM overflow... the 1,800 has 3 x 1.5" bulkheads. And, the Tideline sump has 2 x 1.5" and 1 x 1" drain openings. Which of the three MM drains would you plumb to the 1" Tideline hole? Main? Overflow? Emergency?

 

[ca1ore]

Thank you for the feedback @ca1ore ... since you have experience with the MM overflow... the 1,800 has 3 x 1.5" bulkheads. And, the Tideline sump has 2 x 1.5" and 1 x 1" drain openings. Which of the three MM drains would you plumb to the 1" Tideline hole? Main? Overflow? Emergency?

Main siphon to the 1” sump opening; secondary and emergency to the two 1 1/2” openings.