Jebao DC 12000 intake screen for $1

I have made a inexpensive screen for my new Jebao DC 12000 using a 1.5" PVC schedule 40 adapter with female thread ($ 0.98 at Lowes). I have cut off apx 0.5" from the non-threaded end of the adapter to make it shorter and drilled many small holes around the entire circumference. Then I used a fishing line to create a net inside (kind of like stringing a tennis raquet) and secured the fishing line to the adapter using superglue. Works well to keep snails from being chopped up by the propeller and protects your pump from being destroyed by a random piece of PVC or zip tie...

Edited by Carlsson - August 16 2014 at 10:28pm

Very nice!

That's a lot of fine detail work. Very nice looking yet not a practical solution. Sorry but I'm sure you wouldn't want discover later how the tank suffered because the screen clogged and wasn't noticed until issues started to develop.

It's about the physics of water flow. It will easily clog because of the ratio of small surface area to suction. If the size of the screen is enlarged the intake suction diffuses proportionally at all points.

Here is a great alternative. Have you ever seen how Needlepoint Plastic Canvas can be sewn together with fishing line to make a larger cylindrical screen that practically never clogs? I would be happy to show examples if you are interested.

Aloha 

Jebao DC 12000 does not come with an intake screen (only DC 6000) does.

    The picture bellow explains why this is not only practical solution, but probably one of very few that would work in my sump. There is a very limited amount of space between the intake and the sump wall. This is dictated by my sump's width, length of the pump, and existing plumbing. I can also see directly into the intake, so any possible clogging would be quite obvious. I just can't imagine what would clog this screen as the "holes" are fairly large (maybe a fistfull of astrea snails ).
    I am not a big fan of needlepoint canvas for this application. It comes in 3 varieties: 7, 10, and 14 holes per linear inch. In all cases the holes are much smaller than needed for a screen (not a filter) and thus would be prone to clogging. The "holes" actually make up only about 25% of the surface area of the 10-count and 35% of the 7-count canvas. So, to achieve the same open surface area as in the nylon net screen, you'd have to make a cylinder apx. 1.5" long. Not to mention that all the plastic "bars" in the canvas would create area of very low pressure behind them and disrupt the laminar flow of water into the intake. To avoid decreasing the pump's performance, the cylinder would have to be even longer. Amazon has a screen with 1.5" female thread made by Cal Pump for about $13, but that thing is close to 4" long . Not enough space in my sump for that.




Edited by Carlsson - August 17 2014 at 8:38pm

Oh I have the 6000 so that explains it.

interesting, All the dc 12000 i have used come with a screen, just installed one last week.

What is the distance from the outer end of the PVC fitting to the glass? It looks like only about 1/2". This is important because flow resistance may be causing pump cavitation noise. An easy way to check this would be to remove the DIY screen PVC fitting, thus opening the port to a larger intake area.

If this simple test makes the pump run quieter, a large "basket screen" would be my suggestion. If it were me, I would still swap out the PVC fitting for the benefits of a basket screen, which I describe below. I completely understand what has been said regarding Needlepoint Plastic Canvas mesh size/wire size making usable flow through only about 35% of total surface area. Read on and see how this works.

Using flexible screen material like Plastic Canvas and fishing line, I would take a piece 16"L x 3-4"W and make a ~5"D by ~3-4"L short cylinder. I would sew 5"D round pieces of screen material flat on both ends. A side view would look something like this without the gaps  []  A hole would be cut in one flat end just large enough to snugly fit over the threads of the pump intake port. This hole would be off of center since the threaded intake is only about 1-2" from the bottom of the tank. Because it would be made of flexible screen material, this short cylinder could slide down snugly against the glass, positioning the hole on the back side directly across from the intake port then pushed back over the intake port threads.

The "basket screen" would provide easy flow of water through to the intake port. Here are the calculations:
5" diameter cylinder plus the back screen (5"D x 3.14 x 3"L = 47 square inches (front of screen is only for support of the cylinder shape, since it sits close to the glass)).
Subtract roughly 2" of area occupied by the pump intake port and we have 45".
Now multiply 45" by 35%, the usable flow through Needlepoint as stated in a previous post.
That's 16" of space for water to flow through. Compare 16" with only 2" of water flow through the PVC screen (3.14 x .75" x .75").

I hope this makes sense. The concept is to make the basket screen so large and so far away from the pump intake that water flows through it slow and easy. This is because the suction pressure at the screen holes is far less than at the intake port. Debris may gently sit next to the screen but is not easily sucked up against the screen to clog it. I have done this many times. I know how well it works. The basket screen pictured below worked undisturbed for 8 months with Caulerpa growing all around it before cleaning was eventually required.

Aloha 




Edited by Mark Peterson - September 01 2014 at 8:03am