PVC Skimmer TOTW 8-12-06

[Randy]

I’ve been searching all over for the best DIY skimmer designs and kicked around many ideas. I love the Euro-Reef design but I’m not willing to shell out quite that much or pay for large acrylic tubing.

I’m going mostly PVC but with a large ¼” acrylic viewing pane in the reaction chamber. Unfortunately the collection cup is not acrylic but something that can be upgraded in the future.

So far this is the design:

[bguile]

The design looks pretty well thought out to me and looks like a plan that's not too hard to follow. But then again, I dont know much about designing skimmers. The only thing I can think to ask is what's creating your bubbles? It appears as though the pump will shoot water into the 6" pipe area and I guess hoping the turbulence there will create foam. Is that it? If so, might I suggest some type of "X" (crossing) divider at the outlet of the pump just to divide the water stream.

Also, instead of going through the hassles of melting, bending, and gluing the acrylic window, there is a such thing as transparent PVC. I was just looking at it earlier, I could find the supplier if your interested.

[Randy]

The skimmer will be driven by a Sedra 3500 using a needle impeller. A venturi will be on the inlet.

I've found some clear PVC but I think it's more expensive than acrylic and not quite as transparent. This “viewing pane” is not critical but would be nice. As long as it’s cut right and heated properly in an oven it would shape nicely.

[bguile]

I'm assuming you know that height of your outputs pipe will determine the height of the water in the "basin". Is the drawing to scale? I would think that it's maybe a little too high and you might want to shorten it a little. From the drawing it seems a little to close (height wise) to the smaller opening. Also, I saw in your design on the return that you mentioned cutting the 90 or the "T". You wouldn't have to do either if you found a "street ell", which is a 90 that fits directly into the T without more pipe or modification. Hope that helps. Keep me posted. I'd love to see how it turns out.

[Steven Pro]

That looks like a very nice design, but like bguile, I would feel more comfortable using some clear PVC because I would be too nervous the acrylic to PVC bond would leak. I guess it probably does not matter much if it is an in sump skimmer.

[Randy]

It’s not exactly to scale. This was done using Microsoft Paint. I have some CAD programs but I’m not that comfortable using it yet (though it would have helped greatly).

The stand pipe is adjustable when using the repair coupling so that would make the height easy to alter. I likely wouldn’t glue any of the output fittings anyway (just in case).

it seems a little to close (height wise) to the smaller opening.

Are you referring to the input of the skimmer or the neck?

[Randy]

1-14" fittings are pretty big and even if a street ell was used I doubt it would be quite as compact. No big deal if there's plenty of room. I've cut my fittings before so that a Durso would fit in all of my siphon overflows with room to spare for two 1" siphon tubes. It works every time without flaw or a single problem.

Once the acrylic is heated, shaped, and allowed to cool; I can use Weld On #16 and even drill/tap to screw in some nylon screws. I've been playing with Weld On #16 and it seems to lock tight to PVC and acrylic. From what I understand #16 is the correct one to use.

[Steven Pro]

Do you plan to modify the tapered fitting labeled as floor drain ~2" to get it to mate to the 6" PVC body?

[ANGRY JOHN]

i have also been considering this type of skimmer and a diy self project like this is right up my alley. one thing i was considering is to use a basin box like the pm skimmers so that there is less cavatation inside the skimmer body. i planed on using a baffel to seperate the flow from the output in the basin and this would make the water in the body smooth which i believe would be better for protien attachment. i am going to attempt to do this for a 40 gallon and i dont have specs on the 2500 vs the 3500 so i dont know which is better for my project or the flow rates assoiated with either unit. the last bit which i do not get is why the contact section on most skimmers aren't taller. the longer the bubbles are in contact with the water the better so i will be using at least 24" of tubing above the box to allow for longer contact time. as i see a lot of people adding extensions to there skimmers and they say it works better i figure i will just build it that way to begin with. i think it is great that you provided the drawings and mabe i will work out somthing to show my idea but do not have a good program to workwith at this time. thanks for the ideas though.

[Horace]

I have a DIY PVC needle wheel skimmer that has been running for about 8 months. I have a clear collection cup as well which is VERY easy to remove. I will try and post pictures soon. personally I think your Viewing Window is a waste of time. You dont really need to see inside the thing anyway. You can adjust it by taking the cup off and seeing how high the foam is, also you can make adjustments based on how wet/dry the skimmate is. Granted its not as easy as it would be with clear but making it clear is a pain/expensive. My skimmer currently pulls off about .75 liters (nearly full normal size wine bottle) of semi dark skimmate a week out of my lightly stocked 75g. Thats quite a bit :P

[bguile]

Are you referring to the input of the skimmer or the neck?

I was referring to the neck. The input is fine. I think the skimmer would be best served if the foam has a little more room to collect before it reaches the neck..not a lot though. Since your drawing is not scale, I'd suggest maybe the water level be around half the height of the bottom section.

[Horace]

I was referring to the neck. The input is fine. I think the skimmer would be best served if the foam has a little more room to collect before it reaches the neck..not a lot though. Since your drawing is not scale, I'd suggest maybe the water level be around half the height of the bottom section.

The water level in a skimmer is typically quite a bit higher than that. Normally the water is not all that far, if not right up to the riser tube. If you only have the water half way up, your going to be running it SUPER SUPER dry, and I doubt you would even get any skimmate.

[Randy]

You're right Horace, it isn’t necessary. Someone once posted a link to some cheap acrylic and they carry all sizes of tube, sheet, bar, square, etc… :
http://www.delviesplastics.com/ACRYLIC%20SHEET.htm

After I ordered it I noticed that it was only a few bucks cheaper than US Plastics and US Plastics is only a few hours away from me. I saved in price but likely paid more in shipping. Oh well.

I have total access to some excellent equipment, lathe, saws, etc… so it would only satisfy my curiosities to have a viewing pane. I agree it is not at all necessary.

I’d like to see your pics though, it sounds good.

[Horace]

One thing to consider as well on your molding. If you mold the acrylic sheet to the outside of the 6" PVC, it will be slightly larger diameter than you want. When you go to glue it to the other half of PVC it isnt going to match up just right. I see alot of potential for a leak here. You may be better off getting some huge PVC and cutting it in half and putting a flat piece of acrlyic over the side you cut off. Atleast then I think it would likely seal alot easier.

[Horace]

BTW, I really like some of your design choices...I personlly would like to see a clear cup but you could do that pretty easy by replacing the cup PVC with some sort of other clear container with the bottom/top cut off. THe other consideration you may want to explore is making it recirculating. Mine feeds directly from the overflow and the pump is on a closed loop on the reaction chamber.

[Randy]

I've seen this acrylic method before on RC. This guy heated and shaped the properly cut piece of acrylic. He then cut an appropriate size hole (smaller than the acrylic). He then drilled/tapped properly spaced holes surrounding the acrylic. He uses some silicone as a seal and then used his nylon screws similar to what is shown here:


Weld On #16 could be used but If one were to go through this much effort it would be worth while to make it somewhat removable. I may not do this on the first one.

After the basic build is completed a recirculation pump is worth consideration. We'll see how it goes this weekend.

I'll post pics of the build in process. I just recieved my flat caps and Uniseals today. I already have the rest. I'll be making 2 more after this one so this thread has the potential to be lengthy.

[Randy]

Do you plan to modify the tapered fitting labeled as floor drain ~2" to get it to mate to the 6" PVC body?

I thought about it, but it just didn't seem worth it. The 6" pipe doesn't mate tightly (slip fit) so I will just use Weld On #16. After it's glued I may use another bead where the two meet on the outside.

[Horace]

BTW the Genx pump comes with a venturi already(air inductor). It will work just fine in your application. I couldnt use it for a recirc skimmer though because the design was incompatable.

[Randy]

Major delay: End caps arrived and they don't fit even though they said they would fit schedule 40 PVC . . . they don't.

DO NOT USE THESE:
http://www.qcsupply.com/Products/40.aspx

I'm likely going to use one these:
http://www.savko.com/PartList.asp?pg...tid=17&pid=117
$13.67 each ~ look way too tall ~ could be cut down

http://www.ustubedoors.com/pvccap.html
$12.00 each ~ has those annoying reinforcements, but is only 2.5" tall

Any other suggestions would be greatly appreciated. I've been searching for some flat 6" caps for at least a week and this is all I’ve come up with.

[bguile]

I'm not sure what tools you may have available to you, but I was thinking that maybe you could cut yourself 6.5" "caps" from 1/4" acrylic that you can find at your local Home Depot. I usually find a 18x24 sheet for about $20 (maybe less I'm guessing). You could cut yourself 6 caps and maybe PVC glue will be sufficient. If not, get some Weld-on. Just an idea.