DIY Skimmer

bjohanson1234

bjohanson1234

.........
OK I know that it is generally better to buy a skimmer than to make one. But I am a tinkerer by heart and have been thinking of making a DIY recirculating skimmer.

It is going to be based off of this one that I have found online
Compact Super Skimmer

Here is a drawing of what I am thinking
skimmer1.jpg


Sorry about the quality but I am not good at drawing in paint so I just scetched it on some paper.

It is being built out of 4 inch PVC that I picked up off a job site. It is about 1 foot tall.

The lines for the recirculating pump (mab 5) are going to be 1/2 since that is the size of the fittings on the pump. Same for the water output.

The input is going to be a smaller pump that will attach with a barbed fitting.

There are a few questions I have. How high should the venturi output be in the water column?
I was thinking higher up so that it wouldnt have too much back preasure. Less back preasure means a higher velocity. That would mean that the venturi could pull in more air. :dunno: But the reverse is also true. The lower it is, the more contact time it will have.

Also, what should the flow rate through the skimmer be? The mag 5 has a 500 GPH at 0 head peassure. I know it will be less because of the venturi. Should the smaller pump be pumping WHAT fraction of this?

Well anyways, I am going to go and search for some answeres but if any of you have any input, it owuld be much appreciated.
 
Also, any ideas on making the collection cup.

I am thinking of just getting a 4"pvc cap and cutting a hole in it and glueing some pipe into it.
 
i may have a good collection cup idea, but i will need to take pics of something at the house to explain what i'm thinking, so if i remember, i'll do that tonight, i think you'll like it... its easy...

beond that, i just cant see enough from your drawing to say much right now, either a better scan or sketch, or i'll have to wait till i get home, capture that picture and play with it in some editing software so i can see it...

just from what i can see from here, looks like next time you scan it, scan it as b&w line art, not as a greyscale.
 
dsc01767.jpg


Hope this helps out there.

I am thinking a recirculating skimmer would be better because say I have the mag 5 going at 500 GPH and the input pump at say 50 GPG, then the water would get skimmed 10 times before returning back to the tank.
 
ok, now i can see... hmm well im looking at it and i'm not sure about a couple things...

what direction is the water flow through the pump? the mag 5..

if its going from bottom to top then the venturi is in the wrong place, and if its going from top to bottom, then wont the pump be sucking in the bubbles youve just made rather than the water?

also, wouldnt you rather put a gate valve on the output? the height of the output is gonna control how wet your skimming...
on second thought, maybe the slip is better on this kinda deal, i think it'll actually give you better control.

any plans for a difuser plate?
 
Where would you put the venturi? Before the pump? Wouldnt that just cause the pump to cavitate?

And yes the flow is from the bottom to the top. That way it would be sort of a counter current. Flow going down bubbles going up.

What do you mean by a diffuser plate? Something that will spread the bubbles out?

I kinda want to have all my ducks in a row because once it is built, it will be built no taking it apart except for the pump since I will be having a union in there and treaded fittings going into the body

Brian
 
yes, the venturi should be before the pump, thats the purpose of all these "needle wheel" pumps your allways hearing about, a venturi will let the water suck in the air, but the bubbles are gonna be way too large, use the impellor of the pump to chop them up...

if your flowing from bottom to top then its not really a counter current, and you wont have the dwell time that you think you will cause you'll just be pouring the foamy water onto the top of the column, you should be injecting it into the bottom of the column, that way the bubbles have some up to go, rather than already being at the top...

remember foam fractionation is all about the surface area of the bubbles, and how long they are incontact with the water... the smaller the bubbles, the tighter they can get packed into a given volume of water, thus increasing the oppourtunities for the charges of the amino acids to get attracted and stuck to the surface of each bubble, its a molecular "static cling" kinda thing...

plus by injecting the bubbles at the bottom, they will have much more time in contact as they work thier way up the water column...

you may not need a difuser in a recirc unit, but it was just a thought, yea its just something that helps spread out the bubbles across the diameter of the water column, rather than just having the bubbles comming up in one spot(the output of the pump) again, increasing the contact area and time that the bubbles and the water have together...

also, if you look at most commercial recirc skimmers, the in and the out of the recirc pump are lots closer together vertically than what you have drawn up...
 
yea, after lookn at this, and going back and looking at some of the science of how this works, it makes me wanna go home and try and build a multichambered skimmer....
 
Well, I went to the store and got some supplies.

3 - 4" sch 40 couplings $2 a peice Total $6

2 - 4" caps for I beleive drain pipe. It is not sch 40 it is a thinner wall pipe. But these caps have the same OD as the 4" sch 40 pipe. They are going to be used to make a flat bottom on the skimmer. And to make the collection cup. $2 dollars a peice total $4

1 - 4" coupling for the same drain pipe. I just bought one because I was eyeing up a 2-liter bottle and figured it might slide onto it to make the neck part of the skimmer. $1.70

So far, I have spent about 12 dollars on parts. Have a lot of 1/2 fittings laying around so that shouldnt be a problem.

I am thinking that a 1 1/2 or 2 inch pvc cap with some holes drilled in it will make a good difusion plate. What are your thoughts on that?
 
dsc01768.jpg


Ok the one on the bottom left is a Sch 40 coupling

The one on the right is that cap that I mentioned fits perfectly in the coupling.
One set will make the bottom of the skimmer the other set will make the collection cup.

The one on the top is the drain coupling with the top of a 2-liter bottle. The bottle fits perfectly in there. So just have to think of a way to glue it in real good. I will try just normal pvc glue but not sure if it will bond to the bottle or if it will be so strong that it just melts through it. Gonna just have to test it when I get there.

This will slide into a third coupling that is at the top of the skimmer body.

Will keep you guys posted:Cheers:
 

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