RnB Posted May 11, 2005 Report Share Posted May 11, 2005 hooked up an Iwaki 50 pump as a return pump.... ok so it moves a lot more water then an ehiem 1060 I have now got rid of all the leaks but I have the dreaded micro bubbles..... Pies - others... what causes them, whats the fix. The pump is mounted at floor level, and gravity feeds it from the sump, only about 1 ft of head on the input side, pushing through 2m of tube, about 5ft head. :roll: Quote Link to comment Share on other sites More sharing options...
suphew Posted May 11, 2005 Report Share Posted May 11, 2005 The extra flow down your standpipe could be causing them, ulimate fix is baffles in your sump, otherwise you could try turning the tap on your overflow down just a little bit, not enough to lessen the flow but a little bit of back pressure might stop it dragging down so much air. Next option would be to put some filter wool over the end or under your overflow outlet giving the bubbles a chance to surface before they nit your return. The only other reason I can think of is that your return pump source is sucking in air but I assume you would be able to see this is it was the case. If its the plumbing to the pump, which if it had a leak would be under vacuum when the pump was running and therefore suck in air, you should be able to turn off the pump and see water leak out Quote Link to comment Share on other sites More sharing options...
RnB Posted May 11, 2005 Author Report Share Posted May 11, 2005 lets see if its settled down tonight, but i think it is coming from the return, there is now SO MUCH water flowing through the sump.... and its under the tank in the dark, so very hard to see if the sump has micro bubbles in it...... looks crystal clear at pump input point tho we are not talking heaps just enough to see em if you get close, and they are tiny....... Quote Link to comment Share on other sites More sharing options...
Pies Posted May 11, 2005 Report Share Posted May 11, 2005 It can be caused by cavitation, this is the problem I have. Simply put, my pump pushes more water than it sucks. Check your plumbing, make sure the pipe feeding the pump is larger than the pipe leaving the pump. Or use a tap to reduce the flow out of the pump until the water clears. Pie Quote Link to comment Share on other sites More sharing options...
chimera Posted May 11, 2005 Report Share Posted May 11, 2005 baffles and a bigger sump should fix it - the baffles certainly fixed mine! my input is the same as the output, no micro bubbles. Quote Link to comment Share on other sites More sharing options...
Pies Posted May 11, 2005 Report Share Posted May 11, 2005 You can tell if the bubbles can be fixed by larger sump/baffels. Are the microbubbles being drawn into the sump (i.e visible in the sump)? If yes, bubbles are comming from water being dumped into the sump or from the skimmer. If not its either a air leak or cavitation. Chimera - You probably don't get a cavitation because of the head pressure you pump is under, that is its not able to push water faster than its drawing it in. Cavitation becomes more common the bigger the pump and/or the less head heigh the pump is under. Microbubbles are annoying. Pie Quote Link to comment Share on other sites More sharing options...
RnB Posted May 12, 2005 Author Report Share Posted May 12, 2005 they are "TINY" much smaller then the ones you had the other night. unless they are not buubles, but muck in the water coulum.... pump only been on for 24 hours ..... will opost feeedback tomorrow. Quote Link to comment Share on other sites More sharing options...
chimera Posted May 12, 2005 Report Share Posted May 12, 2005 if the pump has only been on 24 hours, i'd tend to wait. it might settle down. if you do baffles, have 1" gap between them. pies, i DID have microbubbles prior to the baffles - millions of them. baffles made a world of difference as did the height of the water in the last baffle (too low water drops creating more microbubbles) to be precise, cavitation is the rapid formation and collapse of bubbles (vapour pockets) due to sudden increase in pressure. causes wear and tear on the impellor. Quote Link to comment Share on other sites More sharing options...
suphew Posted May 12, 2005 Report Share Posted May 12, 2005 Is there a reason for your suggesting such a small gap between baffles? I would have throught that you would want a gap at least big enough so you could get your hand in to clean them or remove anything that get trapped? Quote Link to comment Share on other sites More sharing options...
chimera Posted May 12, 2005 Report Share Posted May 12, 2005 basing that advice (1" gaps) on a web site i read about a guy who makes sumps. it's more a general figure than anything else. i'll see if i can find the site... pretty sure many of you would have seen it before... in addition to above - it depends on where those microbubbles are being formed. in other words, are the microbubbles formed in the sump causing a negative effect on the performance of the pump OR are microbubbles being formed BECAUSE of cavitation (as described above) on the pump? either method will show microbubbles in the main tank. the first is caused because of a sump badly designed, the 2nd as pies says due to cavitation caused by the pump itself. Quote Link to comment Share on other sites More sharing options...
RnB Posted May 12, 2005 Author Report Share Posted May 12, 2005 I have same pipe side each side of pump... despite what pies has recommended several times, and i agree with him :oops: Quote Link to comment Share on other sites More sharing options...
RnB Posted May 13, 2005 Author Report Share Posted May 13, 2005 coming from return pipe ...... using skimmer + lots of rock as baffles massive improvement but can see a custom sump happing soon...... greatly improved cheers for advice Quote Link to comment Share on other sites More sharing options...
Pies Posted May 13, 2005 Report Share Posted May 13, 2005 causes wear and tear on the impellor. How could a little bubble hurt a ceramic impellor? I found with my sump if the baffels are too close together that the microbubbles just get sucked around and down anyway. Would depend on the amount of flow as well. My new sump has 20cm between baffels. So I can clean it if nessessary, put socks of goodness etc. RnB, you can use icecream containers etc to 'baffle' the initital flow to stop the splash into the sump to begin with. Pieman Quote Link to comment Share on other sites More sharing options...
RnB Posted May 13, 2005 Author Report Share Posted May 13, 2005 mmmmm tip top time ! Quote Link to comment Share on other sites More sharing options...
lduncan Posted May 13, 2005 Report Share Posted May 13, 2005 How could a little bubble hurt a ceramic impellor? The same way it hurts a steel impellor. The shock waves created when bubbles collapse pitt the surface. I'd imagine a ceramic impeller would be a bit more resistant though. Quote Link to comment Share on other sites More sharing options...
RnB Posted May 13, 2005 Author Report Share Posted May 13, 2005 its incredibly destructive force pies.... on a hydrodam spillway , cavitation can literally rip the concrete apart! Quote Link to comment Share on other sites More sharing options...
Pies Posted May 13, 2005 Report Share Posted May 13, 2005 /me has more respect for those little bubbles than he did 15 mintues earlier. Pie Quote Link to comment Share on other sites More sharing options...
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