Very Large Display Tank, Help Appreciated

[Delphinus]

Originally Posted by Troy F

PS: I like the "shark in the roof" idea, I just asked if I could have one and was promptly denied, she thought it would rot and start to smell after a while.

Thanks for the chuckle Troy!!

[Lofus]

I've been reading up on skimmer design and one thing struck me that you might want to consider, The cross sectional area of the skimmer is important, not how you divide it up.

This means that 2 x 6" = 10" or 4 x 4" = 10". This way you could have multiple skimmers so that if you had a problem with one or took one out of service for cleaning you would not significantly effect the tank.

The same sparing philosophy might want to be considered for pumps as well.

[Delphinus]

Lofus, I'm afraid I don't understand what you're saying i.e. 2 times 6 does not equal 10 (nor does 2 times pi times 3 squared which would be the cross sectional area).... Can you elaborate and maybe provide a reference so I can read up on it too?

In my experience, multiple skimmers on a single system does not necessarily equate to a linear increase in "skimming power." I.e., two identical skimmers is not twice the skimming. One tends to outcompete the other. I once read a "tank of the month" or other "featured tank" (I think it was Richard Harker's) where he uses an air driven counter current skimmer as an indicator. I.e., when it starts producing skimmate he knows it's time to clean the other skimmer (I forget what the "other" skimmer was I think it was a large beckett style). Might have been in MFA 2002 where I saw this I'll have to check up on it.

[Lofus]

Sorry Delphinus. The book I've been reading that describes the skimming theory is "Aquatic Systems Engineering: Devices and How They Function" by Pedro Ramon Escobal.

By 2 x 6" = 10" I was referring to a rule of thumb in standard steel piping design but I got the sizes wrong. It should read 2 x 6" = 8".

A 6" sch 40 steel pipe has an ID of 6.065 in so a cross sectional area of 28.8 sq in. Two 6" combined are 57.6 sq in. An 8" sch 40 steel pipe has an ID of 7.981 in so a cross sectional area of 50.3 sq in.

One 8" system or twinned 6" systems behave very simmilliarly. The same holds true for two 8" systems behaving like a single 10" system.

I would expect that acrylic pipe would act the same as steel more or less.

I agree that two different styles of skimmer should operate differently in parallel but two of the same style should operate like one big skimmer.

[Fishster]

That is an awsome project, have you given any thought as to using artificial or trucking in natural seawater?

[Troy F]

Originally Posted by Lofus

Sorry Delphinus. The book I've been reading that describes the skimming theory is "Aquatic Systems Engineering: Devices and How They Function" by Pedro Ramon Escobal.

By 2 x 6" = 10" I was referring to a rule of thumb in standard steel piping design but I got the sizes wrong. It should read 2 x 6" = 8".

A 6" sch 40 steel pipe has an ID of 6.065 in so a cross sectional area of 28.8 sq in. Two 6" combined are 57.6 sq in. An 8" sch 40 steel pipe has an ID of 7.981 in so a cross sectional area of 50.3 sq in.

One 8" system or twinned 6" systems behave very simmilliarly. The same holds true for two 8" systems behaving like a single 10" system.

I would expect that acrylic pipe would act the same as steel more or less.

I agree that two different styles of skimmer should operate differently in parallel but two of the same style should operate like one big skimmer.

There's been a number of people over the years that have run dual skimmers and found only one doing the work.

[StirCrazy]

Originally Posted by Troy F

There's been a number of people over the years that have run dual skimmers and found only one doing the work.

I have seen that posted by two people in the last 2 or 3 years. and both thoes people have tried it using different types of skimmers.

weather this matters or not it could have been becuae one was more efficient than the other and there was a limited amount of nutrents for them to remove from the water.

I thought about it then and I still cannot see why two skimmers shouldent work. they both pull in tank water and there for if they are being run corectly they should both skim. I think the key would be to have them supplied from the same area in order to avoid one being supplied with water from the others discharge.

just doesent sit right with me that one will work and the other won't.

Steve

[Troy F]

I hear you, it doesn't make sense. I guess until someone can afford to put two decent skimmers, of the same type, on the same system, we'll really never know.

[Delphinus]

Not that I really have any idea, but maybe could it have something to do with how fast the DOC accumulates into the water column (i.e. the rate of accumulation) and varying efficiencies of a skimmer to pull it out as it happens... ?? So, say for example if skimmer A is known to outperform skimmer B and we have both skimmers running on a tank, as the fish poop into the water the DOC (or whatever it is we are pulling out with the skimmers) starts to accumulate. Skimmer A starts pulling the DOC out before skimmer B does; thus suddenly the rise in DOC starts to taper off a little bit. Skimmer B doesn't pull out "nothing" per se but it is less than that of skimmer A. Assuming no more fish poop for the moment the DOC starts to drop a little bit and thus for the moment there's nothing new to pull out. Until another fish poops again, and so on.

IF this theory was somewhat close to reality then it would suggest that two skimmers of identical abilities would both be pulling out gunk equally.


But .... I have no idea if it "really" works this way at all or not. I'm just thinking out loud for the sake of seeing if anyone else has a theory about it ...

cheers

[StirCrazy]

um.. ya Tony, exactly what I said in the second paragraph
"one was more efficient than the other and there was a limited amount of nutrents for them to remove from the water. "

Steve