skimmer science

overflowin

overflowin

New member
ok, i have a 6 foot tall, 10" diameter cast acrylic tube, and 2 sedra ksp-5000 needlewheel pumps. i want to build a recirculating skimmer using both pumps, and a length of the acrylic tube to be determined.

My display tank is a standard 125 with a somewhat light bioload currently, but i am adding a 100g frag tank to the system, and would like to upgrade my display to something in the 300g range next year...

given what i have, pump wise, does anyone have any recommendation on how tall to make the reaction chamber? i would like to build something that will be appropriate for my current system, but still be able to hang if my wife lets me upgrade next year. i've looked, and haven't found any skimmers that use the dual 5000 setup, but i'm sure there's some out there.

I'm also wondering if the tapered top really increases performance so much that it is worth the extra work. i had planned on building an elaborate jig to heat form a cone for the top of the reaction chamber up to the neck, but didn't know if it was really worth it...

i'd also like any input from the diy'ers out there on feed pump size... my system currently doesn't make feeding from a drain a realistic option... i was thinking a mag 2 or something comparable...

thanks for the help, and i'll post some pics once i get the project started...

Donnie
 
To be honest, there isn't any science involving skimmer design, not really. Since all skimmers, regardless of design, will remove about the same amount of organics ( ~30%,) it really does not matter what the physical topology of the skimmer is.

If looking for some 'design criteria,' there are some rough recommendations:

1) Will process ~2x - 3x the system volume per hour. (Largely arbitrary, but better than serves X gallons.)

2) The smaller the bubble size, the more 'efficient' the process, depending on...

3) Contact time (there is no formula, or published method for determining an appropriate contact time.) and..

4) The concentration of TOC in the skimmer influent. (The higher the concentration, the 'more' efficiently the skimmer will remove the 30% of the TOC.

From this, you can draw some conclusions:

The design of the skimmer does not make any difference. How the air and water are introduced to the skimmer, does not make any difference. Recirculating skimmers do not perform any better than single pass skimmers, and probably reduces the efficiency because the second time around, the concentration of TOC will be lower, and the skimmer may well not remove anything at all...if our aquariums were single pass systems (which they are not) perhaps a recirculating skimmer would make sense, but that would be pushing it. Also, from this one can conclude that the flow rate past the skimmer's inlet, has nothing to do with the skimmer's performance either. (Aquariums are not single pass systems.)

There is a relationship between the amount of air introduced, and the amount of water introduced, but again, there is no published method to determine these values, for a skimmer of a given size, (short wide body for instance,) and all but one design do not allow independent adjustment of the air and water flow (adjusting one does not affect the other.)

Without the capability to utilize chromatography (gas, HPLC, what have you.) There is no way to determine how your skimmer is actually performing. Lacking that capability, there isn't any science that can be applied to the design, and it is best to copy (blatantly) another design, or:

Build an airstone driven counter current skimmer, in which you can play with the air flow, bubble size, and flow rate (contact time) till it works good. The oldest design (next to the co-current) still works just as well as any of the modern designs, and in some cases better. The only drawback is they do require some maintanence (replacing airstones rather often.)
 
Ok, so there's no actual science to it... how bout some experience based suggestions on reaction chamber height, value of tapered neck and feed rate.

I was planning to build a clone of a proven design, but haven't found one using the pumps I already have...
 
A 10" ID skimmer would need to be overly tall to handle a well stocked 300... maybe only 24"-30" plus the drying tube & cup. In addition, 2 Sedra 5000 pumps may not yield the bubble density needed in that big body. Build a mocked up prototype first to see how the pumps work in the configuration you have in mind.

FWIW, I don't think the cone at the top of a skimmer helps much.
 
reefgeezer said:
A 10" ID skimmer would need to be overly tall to handle a well stocked 300... maybe only 24"-30" plus the drying tube & cup. In addition, 2 Sedra 5000 pumps may not yield the bubble density needed in that big body. Build a mocked up prototype first to see how the pumps work in the configuration you have in mind.

FWIW, I don't think the cone at the top of a skimmer helps much.
Click to expand...

Just realized I made a typo... I should have typed "A 10" ID skimmer WOULDN'T need to be overly tall"... sorry if I caused any confusion. :wavehand:
 
IMO with 10" dia tube.. a 12" total reaction chamber is PLENTY..
You've got 4-6 skimmers there with that 6ft piece.

I'm starting my DIY Tunze 9415/30 "clone" next week once I get my cnc machine back up and running. :) I really like that features/simple design of those..
 
G4 and g5 were (are) sedra 9000's... thanks for the heads up on the tunze skimmer. I think a short stubby reaction chamber will be the ticket.
 
uncleof6 said:
Cone type skimmers, when they were introduced, were just a sales gimmick in order to stimulate sales as something that is a 'must have,' 'new and improved,' intended to get people to buy a new skimmer, that accomplished little or nothing in terms of performance. Regardless of the design, they all perform relatively equally.

Here is a relatively narrow needle-wheel design...

http://www.beananimal.com/projects/6-needle-wheel-protein-skimmer.aspx
Click to expand...

I recently have been reading about skimmers, and from what I have found you are right. It seems like a lot of the really expensive skimmers out are VERY not worth it.

here is some engineering and "science" behind skimmers if the OP is interested.

http://www.advancedaquarist.com/2010/1/aafeature

In my opinion, an appropriate sized mid to low cost skimmer is has the best cost/benefit ratio. Anything fancy and expensive is just hype
 
You must log in or register to reply here.

Similar threads

S
Small Sump Leak - Worth fixing?
Replies
1
Views
110
griss
griss
S
Novice Aquarist - Sump & Equipment Questions
Replies
9
Views
304
wvned
wvned
F
DYI Perestaltic Pump Kit
Replies
0
Views
1K
Fishkin
F
S
Overskimming on New Protein Skimmer
Replies
2
Views
124
wvned
wvned
K
Need help with Sicce MicraPlus Pump Mod for Fluval Evo 5 Tank
Replies
0
Views
172
kingyking888
K
Back
Top