how to get even flow?

[anders moon]

this is my second ATS build...

This time I cant get the flow even across the screen! I have used 16mm pipes and the slot is about 5mm thick... How do you do it???

[anders moon]

now I have tried with a different pump that can go down in flow, but it seems too much aswell???

Do i need a larger pipe or Have drilled the slot too wide???

This is very disapointing because what I really want to spent time on is my new led light!!!

[MorganAtlanta]

Even flow is tricky to get. 5mm sounds wide. More like 3mm is usual, I think. If the slot is too wide, you will get lots of flow shooting out near the inlet and little flow on the far end.

[Doompie]

5mm is indeed a little wide. What pump you use?
I just used a grinder with a disk to grind metal and a steady hand to get a 3mm slot in a 25mm pipe. (don't grind it trough at once, then the plastic will melt, I think I did at least 10 grinds before it was trough)
Total slot length is 58 cm with 2500 l/h pump (acual around 2000 l/u). which spreads out evenly over the full length of the slot.

When you're slot is not equally wide over the length you can get flow problems, water always finds the easiest way to get out.

[anders moon]

the pump is a aquabee 2000/1 and can aprox. deliver about 1500L/H when the water is lifted 1½meter upwards.

Last evening I liftet up the far end of the pipe and that helped a little. I have downsized the pump a little and that helped...

I will try to cut the slot a little longer (3-5mm) because the canvas is a little bended...that could help the water to get out in the beginning

the flow is strongest in the far end that is a little strange :roll:

I have used a metal cutter (I dont know the word in english) to cut the slut, very carefully...it is tricky!

[anders moon]

I have now cut the slot so that the canvas fits in the length. But my problem is stil that the flow is strongest in the far end of the pipe???
Only when I almost closes for the flow, the flow comes out in the beginning of the pipe but then there are no flow in the far end. The slot is 5mm in the beginning and about 3mm in the far end of the pipe and the pipe is horisontinel...

What to do???

[kotlec]

I'd bet your slot is too big for flow you have. There is no water pressure inside pipe. Water firstly flows where is least resistance ( pipe diameter bigger than slot) then falls away thru end of pipe. This is very complicated to make flow even in this situation.
Easiest way to fix - stronger pump.

[anders moon]

(my message dissaperared I´ll try again)

It is only when I cut down on flow it comes out in the beginning of the pipe, when the flow is on max it shifts and comes strongly out in the far end of the pipe.

I already tried a stronger pumpe with 3000L/h with the result of chaotic/splashy and noisy flow in the far end of the pipe, what did I do wrong?

will it help if I make another slot entirely with a 3mm slot so that the canvas fits better? I just thought that a wider slot would give me the stronger flow (I can adjust my pump)...

Dammit this flow issue I want to play with the led light!!!

[kotlec]

Thats really mystic then. Did you try adjust pipe angle ?
What is flow pattern if you remove screen ?

[RkyRickstr]

Try this.. use the bigger pump and put an elbow right before the scrubber tube... This avoids the jet like stream of water..

[Floyd R Turbo]

a 1/8" slot, or 3.175 mm is what is generally recommended if you are using the #7 Mesh Plastic Canvas, which is about 1mm thick and leaves 1mm of slot on either side.

I think your problem however is the uneven cut of the slot. It is key to even flow is to ensure that the slot is straight and even width. If it's not straight, the screen can get flow blocked to areas. If it's not even width, then the flow will vary across the screen. Also key is cutting the slot such that the screen can hang perfectly vertical, which means the cutter must me at a perpendicular to the tube while cutting if this makes sense. The screen needs to basically hang freely, only held in place by the zip-ties.

You can make the slot a little wider, I think mine is probably close to 4 or 4.5mm and I currently run less than ideal flow across it, 22" slot with a Mag 5, and the flow doesn't start out completely even after cleaning, but one day later it's perfectly even.

Bottom line here is that you need to cut another slot tube. Take your time and do it right, mark the slot and cut it straight. Start with 3 or 3.25mm, hook it up, check the flow, widen in small increments as necessary.

[anders moon]

alrighty!
I apreciate all of your help all of you! Tomorrow I will buy some more pvc and a dremel cutter disc, then I will be able to cut the slot more accurate! update vill come soon!!!

[anders moon]

Now I have cut a new slot witha dremel cutter, this was a success!!!

My old ATS was build with a different canvas which was thicker... that were the reason why I didnt think it was the sot that was the problem! Good advice Floyd!!!

I salute all of you guys that helped me