Skimmer rating ?

So when the skimmer is rated for say 150 gallons, is that tank size or overall water volume.

 

That is generally the entire system. to add to that the skimmer's gallon rating is also usually based on a lighter bioload.

Basically - if you have a heavily stocked system full of LPS/SPS corals you need to double the gallons of your system to get the skimmer you need.

I have a 130-140 gallon system with a skimmer rated for 250 gallons just for reference.

 

So if I am going with a 90 gallon tank, 30 gallon sump for 120 total volume, then I should have a skimmer rated for about 240 ?

 

A quality skimmer would be rated for dt size and lower quality who knows how they determine. Example i have a euro reef 135 good for 135 normal bio load. I think they say about 400 gal total system. Then i have a prizm pro i think they rate for over a 100 gallons, but isn't even good for the 55 gal it's on.

 

What are you putting in there?

If just softies/LPS and few fish - that would be a bit overkill even.

If you plan on having full bioload and SPS/LPS dominant - then that's about right. Just remember tho - even though your tank is 90 gallons and your sump is 30 - you actual system volume is a bit less. You are looking at more like 65-70 gallons in your DT (depending on how much sand/rock) and in your 30 gallon sump - probably more like 20 gallons. So you are looking at a total system volume of roughly 90 gallons or so.

 

I disagree on ratings. Most skimmer makers put out ratings for light and heavy loads. Don't even look at light... just go by heavy. 90% of people in this hobby all end up at a heavy fish load in the end, so it is the only number you need to worry about.

A skimmer... by a quality name brand popular maker.... will do your tank fine at rated load... that is what it is rated for. Most will go over that. I like to shoot for 125-150% of your tank size. Not because it will work better... it won't. It's because if a fish dies or something goes bad it will have some extra head room to deal with it.

There is no reason to just double the skimmer size just for giggles... unless you want to uses more power, take up more room, and enjoy spending more money than you should. The only reason to buy one twice as big is IF you KNOW you WILL be going bigger in the near future and are preparing for that.

 

I agree with Powerman. 125% of total water volume.

 

I think powerman said tank size. In cj's case i would look for a skimmer with a 120 heavy bio load and if my budget allowed i would up size one. However if my aux system say held another 90 gal i would still opt for same skimmer.

 

To be clear I'm talking about total system volume.... that is what will determine your fish load and that is what you need to size your skimmer for. My 90g with a 60g sump/fuge only had a total ACTUAL water volume of 110g.

 

I've been known to be wrong but my thinking is as i increase water out of the dt i am decreasing bio load on system. Therefore say rated skimmer 100 gal heavy load, 200 gallon light load.