Skimmer sizing?

[Bigroost]

I am setting up a system with a 40b display and a 40b sump. I am guessing 70ish gallons maybe a bit less. I can't decide between the Reef octopus 110 int or the 150. My main concern I guess is that the 150 would be overkill. Thoughts?

I know this has been covered ad nauseum but every time I get to searching and reading I lose track.

 

[slief]

Base your skimmer choice on your display size. That is how skimmers are typically sized. They don't base them on system volume contrary to popular thinking. If you go too large, there won't be enough dissolved organics in your system to maintain a consistent foam head and your skimmer will inconsistent as a result.

 

[markandamb]

I agree bigger is not always better..

 

[Smoke_N_Reefer]

A lot of folks say double your DT volume. A skimmer rated for around 100g maybe 150g will be a good choice for your system.

 

[mikeatjac]

A lot of folks say double your DT volume. A skimmer rated for around 100g maybe 150g will be a good choice for your system.

Base yor skimmer on the DT volume.

 

[slief]

A lot of folks say double your DT volume. A skimmer rated for around 100g maybe 150g will be a good choice for your system.

Poor advice is apparenly being given to you by "a lot of folks". The people who would make a blanket statement like that would be people who don't necessarily know what they are talking about or people that base that statement on experience crappy skimmers. That kind of methodology won't work with most of the high end internal skimmers let alone most skimmers from reputable manufacturers who rate their skimmers properly. I can tell you that with an awful lot of first hand experience.

On the flip side, there are some skimmers you can do that with. It largely depends on neck sizing but also comes down to the amount of fish in the tank along with feeding, whether you run filter socks or other mechanical filtration or not as well as what the tank has in the way of biological filtration. Either way, a decent skimmer should be sized based on display volume and not 2x display volume or even 1.5x display volume unless you like incosnistancy or like dealing with constant overflows because you have to adjust the skimmer so wet just to get it to produce anything.

 

[ca1ore]

Basing a skimmer on display size is a proxy of course. I've asked a number of manufactures how they judge such ratings. Is it based on some elusive 'medium stocking' level .... or something else. I never get an answer that fills me with great confidence that it's anything but a WAG. What we really need is some kind of model where you can input your fish, corals, inverts, amount of live rock .... Along with any 'competing' filtration methods .... And it outputs an organics 'rating' that you can then use to select an appropriately sized skimmer. Do the skimmer manufacturers attempt something like this? Maybe they do and I'm happy to stand corrected; but if they don't then ascribing much accuracy to their ratings seems silly to me. Are there even standards of assessment that they all use? I doubt it.

 

[rburns24]

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Go with the 110. The 150 would be way too much.
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[metalmesh]

Basing a skimmer on display size is a proxy of course. I've asked a number of manufactures how they judge such ratings. Is it based on some elusive 'medium stocking' level .... or something else. I never get an answer that fills me with great confidence that it's anything but a WAG. What we really need is some kind of model where you can input your fish, corals, inverts, amount of live rock .... Along with any 'competing' filtration methods .... And it outputs an organics 'rating' that you can then use to select an appropriately sized skimmer. Do the skimmer manufacturers attempt something like this? Maybe they do and I'm happy to stand corrected; but if they don't then ascribing much accuracy to their ratings seems silly to me. Are there even standards of assessment that they all use? I doubt it.

As a company who has made skimmers for the past 30 years after we had a salt water reef shop for 10 years, I can tell you that there is absolutely no way for any skimmer manufacturer to specify with any accuracy the correct size skimmer for a particular aquarium.
Not only are there too many variables associated with any aquarium, skimmer performance is yet another variable thrown in the mix.

All that said, I have learned to look for:
1. Water clarity and color, must look as if there is no water in the tank.
2. No nuisance algae growth ( assuming no phosphates present)
3. Health of the animals, specifically corals ( assuming good lighting)
4. Less and less skimmate being collected until an equilibrium is achieved (assuming no large variations in tank inhabitants and skimmer is performing the same as before)

As you can see, there are even more variables ( assumptions) which have to be taken in consideration in judging the proper skimmer size/performance.

That is why hobbyists try one skimmer after another in search of the Utopian skimmer.
What ever your initial choice there are two parameters in judging skimmer performance that establish the efficiency of a skimmer;
1. Amount of foam produced
2. Most important the size of the bubbles created, the smaller the better because of the increased overall surface area to which the organics can cling to which increases the speed of removal of unwanted organics.

Hope this helps some.

 

[Bigroost]

Thanks for taking the time to answer my questions, a lot of good info in there. Going on a 40 gallon display is their a smaller option I should be looking at or a more cost effective option?