5' Skimmer Build in Progress

Well, I finished building it today. I wet tested it, and no problems. I went to install it, and I made it a little to wide to fit in the sump. Hind sight....... Additionally, I need a fitting from the home center to plumb the feed line. It should be done tomorrow...
 
The skimmer cup is a combination of pieces:

6" PVC pipe is the body
1/4" Acrylic plate is the bottom and top.
3" pipe is the neck
3" coupler is the attachment to the skimmer riser

I cut a 1/2" off of the coupler.
I cut a hole that perfectly fit the 3" pipe out of the bottom of the cup.
I put the coupler (cut side towards cup) on the outside and the piece on the inside. This sandwitched the cup in the middle. I then inserted the short 3" pipe from inside the cup. When the glue cured, I ran a bead of weldon 16 around all the seams to create the seal.
This created a cup that will sit on top of the skimmer riser neck with a friction fit between a coupler and a pipe.

I will try to take a pic of the finished cup tonight.

Dale
 
Well, I just finished up the initial install. The flow meter for the recirc line is quite the eye opener. I installed the pump with only 2' of head. I am getting about 100 g per hour. Not bad considering the 700 gph for a mag 7.

I ordered the second flowmeter, and will install it on the feed when I get it.

I will get the air meter in maybe tomorrow.

The airbubbles are rising faster than 3 cm/s. The bubbles are a little on the large size. My air pump seems to be lacking as well. I guess the 5' of head is more than I bargained for. I will be able to tell when I get the flowmeter in. We will see what kind of foam head I get overnight and the next few days.

Dale
 
The output on the Mag sounds a bit strange: a recirculation pump is essentially a closed loop. This should give you zero head pressure coming from the height difference - though obviously pipe friction and bends will degrade the output.

You mentioned the air pump was a bit underwhelming, do you think it is because the pump can not put out enough air (CFM) or is it because of the 5 foot of water pressure? I ask because a bigger pump by the same company should solve the CFM problem, but might not be a solution if water pressure is the issue.

Any thoughts about changes to the skimmer? I am very interested as I was going to build the exact skimmer you have, but saw your post just before I was going to order everything. I really want to build this thing, but I want to wait for your suggestions/opinions. Many thanks for taking the time to post your efforts and results. Timing is everything - and for once it was on my side :rollface:
 
chlupl - The tank is a 90 g with a 100 g sump and 20 g refugium.

JC Pollman - I was quite surprised at the flow rate. Before I turned on the air, the rate was at 150 GPM. Now after the air is turned on, the effective water height in the body is reduced. This creates less force feeding the pump. This inturn requires the pump to work harder to push up the head pressure. The surprising thing was the small amount of head that created such a drastic difference. I used 1" pvc for the plumbing. I converted to 3/4 hose for the flowmeter (pump is 1/2). There are a few 90's in the system. Quite frankly I now 90's effect flow, but I only wanted about 180 GPM. I thought I would need a bleed off loop to control pump output. I did install the recirc loop from the pump outlet to the pump inlet, but I have the isolation valve shut so all output is directed to the skimmer.

As testing continues, I will post updates.

I will post pictures either tonight or over the weekend. Next week is a holiday for us, so I will have a little more time.

Dale
 
hmmm those air pumps are rated for 80feet deep... I cant imagine how much pressure there could be with "just" 5'. some, sure. but enough to really affect it? seems strange.

have an pics? the mag 7 should be pushing atleast 600gph in a recirculation role. 150 isnt right at all.
 
<a href=showthread.php?s=&postid=6340630#post6340630 target=_blank>Originally posted</a> by areze
hmmm those air pumps are rated for 80feet deep... I cant imagine how much pressure there could be with "just" 5'. some, sure. but enough to really affect it? seems strange.

have an pics? the mag 7 should be pushing atleast 600gph in a recirculation role. 150 isnt right at all.
Click to expand...

I am not sure of where you got your info, but my pump will not put out more than 3 psi. The higher the psi, the lower the output volume. Now I do not know what 3 psi equates to in depth, but I am pretty sure it is short of the 80 feet.

I am going to google it.

Dale
 
Here is a quick approximation formula I found.

pressure (lbs-per-sq-in) = depth(ft) * 15(lbs-per-square-inch-per-atm) / 33(ft-per-atm)

So my pump:

3 psi = X * 15 / 33
6.6 feet = X

So it looks as if I ordered the wrong pump. The Aquatic eco pump curve shows a rapid decline in performance as the pressure increases.

As soon as I get some 1/8" nipples I can plumb in my air flow meter.

Dale
 
hmmm yes your correct. I was looking at a different pump and even so I saw feet, though it was inches. 84 inches, not 84 feet.
 
Well, I just ordered a new pump and stones. I will be adding a section to my skimmer calculator to calculate out the air pressure needed to overcome the water pressure.

Aquatic eco quoted 27.7" of water = 1 psi.

In my case I have a little over 2 psi for the water. The stones add another 10 " of backpressure. Then there is the line loss. I failed to properly size my pump. My biggest failure was in the bubble rise rate.

My bubbles rose so fast that I need a lot of make up air to keep the 13%. This is a result of bubbles that are to large. Since they are so large they rise faster. Since they rise faster I need more air. So i ordered the fine pore stones and the LT19 Whitewater pump. The LT19 will do 1 cfm at 3 psi. This equates to 83" of water.

I have 60" of water + airstone backpressure ~ 10" = 70". This equates to 2.5 psi.

Dale
 
What size stones - and how many?

I remember reading somewhere that it is better to under pressure the stones, so I would think the 6 inch stones might be better than the 3 inchers - to bad they do not make them 4.5 inches long. However, maybe a 6 inch stone can be cut down to 4.5 with no issues?
 
I ordered 3 of the ALR80 stones.
They are rated for .35 cfm each. I need .7 cfm, so mine will be underdriven.

The inside diameter of the pipe is 5.75 inches. You have to be careful, cause the stone inlet takes up space as well. You are only dealing with a 4" square inside the skimmer body.

Dale
 
I used the sweetwater 2 stones of 9" length on my 1.5 whitewater pump. I used 6 of them though. Same approx chamber height and 6" as well. Seems to work out well. I can easily make a very dry skimmate which is so dry it stays as bubbles in the collection cup. If I do a wetter skim which I like it gets a little tricky to not overskim. I had used those rena microbubbler 6" cylinder ones on my 4" skimmer which was about 5 ft chamber and it worked great. If I can't get these expensive stones to fine tune a little better, I may go back to those.
 
<a href=showthread.php?s=&postid=6345216#post6345216 target=_blank>Originally posted</a> by DrBDC
I used the sweetwater 2 stones of 9" length on my 1.5 whitewater pump. I used 6 of them though.
Click to expand...

Any pics? Did you use a manifold for the stones, or individual air lines?
 
I took a stone with me to Lowe's and found a nylon screw in fitting that took a plastic line to the other side. Like one for an ro/di line. But with 6 of those stones in there the couldn't lie flat so they barely fit vertical. I haven't tried it with any other number but I may try. It's working, nitrates are 0, I should probably leave well enough alone. My feed pump is a mag 3 but I have that throttled back about 1/2 with a ball valve. After trying to figure head loss I came up with about 220ish before the valve. I was trying to aim for about 120ish.
 
I have a mag 7 installed on a closed loop. Admitedly I have several 90's, but I did use 1" plumbing. When I added a flowmeter, I was shocked to see 150 gph.
 
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