Return pump - tons of tiny bubbles- HELP!

[westwind77]

I have reached a point of major frustrations right now and I need some help! I purchased an Eheim 'hobby pump' model 1260 (634 gph with a max head of 12.1 feet at 65 watts. Input 25/34 mm, output 16/22 mm.)
I have 1" pvc going into the tank (110 X-high) about 24" down, that comes out into a 1" 90 degree fitting, then about 4 inches of 1" pvc, then another 90 degree 1" fitting, then about 12" of 1" pvc, then into a barb which attaches to the 25/34mm Eheim hose which runs the rest of the way to the pump on the floor. I am getting air/tubulance somewhere in the pick/up line and when the impeller hits those bubbles and it shoots them out the return my tank turns into a bubble cloud! What can I do to fixt this?!
Originally I tried to use a small pick-up tube then 2 barbs to expand the width to attach to the 25/34 hose, but as soon as i started it up you could seen clean water enter the hose up the barbs, on the other side of the barbs larger bubble were forming and doing the same thing as described above. I figured by increasing the size of the pick-up system I could reduce the flow rate and not have the bubble issues, but I was wrong!
I do not know what else to do at this point? All pvc connection are tight and adhesive sealed so no air is coming from there. All tube to barb fittings are tight and clamped so no air is getting in there either.
How should I set this up so I do not get any air? Do I need to take everything apart and sand down the inside edges somehow so they are round as not to have a sharp edge to cause turbulance?
I would have just purchased some kind of pre-built pick-up system but I could not find one on-line anywhere so I had to make my own.
Please, any help would be greatly appeciated! Thank you!

 

[bang guy]

Your impeller is cavitating. Using 1.25" as input all the way to the pump will solve this or your can restrict the output with a valve.
This is a common problem when using a pressure rated pump on a closed loop (that has no head to push against).

 

[westwind77]

Originally Posted by Bang Guy
http:///forum/post/2866045
Your impeller is cavitating. Using 1.25" as input all the way to the pump will solve this or your can restrict the output with a valve.
This is a common problem when using a pressure rated pump on a closed loop (that has no head to push against).
I can see air coming down the pick up tubing, the impeller it just turning the larger bubbles into millions of smaller ones. If I go up to the 1.25" how will I attach it to the in-line pump? The barb that is provided is for the 25/34mm hose, I still would have to reduce it at some point. Is there a place that sells threaded ends with 1.25" barbs? I could go to a local plumbing supply store but they dont have a large selection around here.

 

[bang guy]

Restrict the output and see if the bubbles stop. If the bubbles don't stop when the output is slowed down to half then it's probably an air leak.

 

[westwind77]

I fixed the problem! I took all the plumbing apart and filed/sanded all the inside edges so they are tapered, allowing the water to flow smoothly, not running into any hard/sharp edges of the pipes, like before. Water circulates throught without a single air bubble! I really am surprised more people do not run into this issue.
I also installed a 300w Hydor ETH In-Line Heater to the system and it still remains bubble free. I was concerned that with the GPH being close to 700 that the water would be moving too fast and the heater would not be able to make enough contact time with the water to heat it. I turned off the in-tank heater and so far it seems to be working, even raised the tank a degree so far!
I think I am very close to being happy with my set-up. I will post photos soon!
I modified and drilled my Orbit light to accept the SunPod hanging kit also, looks so much nicer than on the plastic brackets, and it was really simple and easy!