# Pump Volume. Is there such a thing as too much?



## JoeGoFish (Feb 5, 2012)

I am setting up an 85g salt tank and plan to add fish and coral in the future. I've surveyed many shops, talked with dozens of people, and sought advice on this site. My question remains: What is the right size pump to install to ensure proper flow?

The tank has an in-tank bio-mechanical filter with an overflow box and return port. I've been told 3x volume, 4x volume, and even 6x volume. The prices for these pumps vary widely, so I'd like to make the purchase one time and move on.

Keep in mind, this question is related to a non-sump circulation pump, not a wave maker, or other pump.

What say ye?


----------



## Crazy (Mar 1, 2012)

I think the best answer is that although you want a good amount of water flow, you don't want your aquarium to resemble a washing machine. I would go with approx 3 to 4 times volume on a tank your size because if your pump sets in the cabinet you will lose head pressure on the way up the return valve. My main rule of thumb is to go by the head pressure rating. If your tank sets 4 foot off the ground at the top of the rim then get a pump rated for 8 so it is no stress on the pump. You can always modify the plumbing to increase the head pressure and slow down flow, but you can't make a weak pump push more.


----------



## Reefing Madness (Aug 12, 2011)

Fish o ly tanks require minimum of 10x the water turnover, Reef tanks require a minimum of 20x yiur water turn over. So for your tank I would suggest starting at 1700gph. Freshwater has the turn over rate of 3-4 times, saltwater is a different beast. Example, I have a 240g tank with 6400gph flow using 2 powerheads, up until recently I was running 8800gph, and did not think that much was neded, so I cut back.


----------



## JoeGoFish (Feb 5, 2012)

This is exactly what I mean. I was just in a reputable saltwater shop, and the owner, who has been keeping corals for 15 years, told me 3-4x is minimum, and 6-8x is ideal for the primary pump. He suggested I supplement with a 6-8x in-tank pump. That's 33% of your recommended volume. Beyond reef versus fish only, what other variables do I need to consider? 10-20x intuitively feels like overkill, but I'm open to hearing more. Are there pitfalls to 6-8x turnover?


----------



## Reefing Madness (Aug 12, 2011)

Your looking at dead spots in your tank, those areas will trap and collect debre and cause water quality issues. The higher flows are for some corals which require that flow to thrive, that's why 20x flow rate is stated as a starting point. The lower 10x flow is to keep debre suspended so that a sump or skimmer has a chacne to get it out of the water column.


----------



## JoeGoFish (Feb 5, 2012)

Excellent information. Thank you for the deeper dive.


----------

