Hello; If I read and understood correctly the OP seems to be saying that there is not a way for any air to be sucked into the system. Otherwise air sucked into the pump would be a neat answer. It also is a somewhat recent thing.
Mirco Bubble Damages?
- Thread starter benzjamin13
- Start date
Hello; If I read and understood correctly the OP seems to be saying that there is not a way for any air to be sucked into the system. Otherwise air sucked into the pump would be a neat answer. It also is a somewhat recent thing.
Info from me (a fuel systems engineer, so I deal with cavitation A LOT
).Cavitation damage is caused by the collapse of the vapor bubbles. It could errode the impellar. But I don't really see it happening due to micro bubbles in the water in these types of applications. My AC110's cause a lot of micro bubbles in my water column, and I have yet to see any cavitation damage to my impellars when cleaning them.
The main theory behind cavitation is that the formation and subsequent collapse of vapor bubbles is due to a combination of sudden pressure drop (as seen through an orifice for example) and an initiation site for the vapor (such as a particle of debris). But it's the collapse of the vapor bubble that does damage if it collapses next to something. Think of the collapse as like a small implosion.
So.....Since cavitation damage is caused by the implosion of the vapor bubble, you wouldn't see it as micro bubbles in his tank since the bubble would implode and changed state back to liquid near the impellar if this were truly happening (which I don't believe it is).
So.....We can rule out cavitation damage since he's seeing micro bubbles in his water column! (well, it could still happen if some (but not all) bubbles were collapsing near the impellar surface, but I really don't think you are getting that extreme of pressure drop to induce cavitation on an eheim canister unless you put a small orifice in front of the motor to induce a pressure drop)
Hello; Re-seedubs1, Could a restriction in the inlet side of a system be enough to create the conditions you describe? I am thinking of something along the lines of debris clogging an intake screen, a build up of of gunk along the internal surfaces of intake pipes ahead of the impellers or perhaps a chunk of something large enough to be stuck inside an intake tube?
The Op said that the system had run without the bubbles for a good while and the bubbles had begun later.
I have had a fairly thick layer of sticky gunk adhear to the inside of filter tubing after a long period of running. The kind that would not rinse out and had to be dislodged with a brush.
The Op said that the system had run without the bubbles for a good while and the bubbles had begun later.
I have had a fairly thick layer of sticky gunk adhear to the inside of filter tubing after a long period of running. The kind that would not rinse out and had to be dislodged with a brush.
I know when my FX5 starts doing this it means that it's either super dirty and needs to be cleaned out or that it is packed with too much media. The micro bubbles are a result of lower water flow rates.
Yes, it is a possibility... Depending on the pump design. If you had a very high power high pressure pump then cavitation is a possibility. BUT the vast majority of aquarium pumps especially the ones found in "Normal" sized aquariums simply do not have the power or impeller design needed to create the severe low pressure needed to have to worry about cavitation. Fuel usually has a much lower vapor pressure than water hence it will spontaneously vaporize at less sever conditions than water making cavatation more likely to occur. I am most familial with cavitation in pumps as it is associated with hydraulic pumps. Many hydraulic pumps are positive displacement pumps which can create a severe vacuum when the incoming flow is blocked. This severe vacuum causes the cavitation condition where the hydraulic fluid spontaneously boils at a very low temperature and cavitation occurs.
Maybe a pool/spa type pump might have the power to generate the vacuum needed for cavitation... but I do not know enough about these styles of pumps.
A normal magnetic drive aquarium pump is simply not powerful enough to generate the severe low pressure condition need for cavitation. I specifically mention magnetic drive pumps because I believe (without any substantiating evidence) that the magnetic drive would decouple before a cavitation condition is created. In actuality I believe the impeller design of these pumps would more likely create a condition where the impeller is just pushing around the water in the impeller housing without actually moving the water through the system. When the impeller is just moving water around the impeller housing the motor will actually speed up and the current being drawn will actually be reduced because the pump is no longer performing the work of pumping water.
If you are seeing microbubbles in your pump output due to incoming line blockages these are most likely due to sucking air through a hose seal... not cavitation.
Fell free to correct me if I am disseminating false information.
Howdy,
Cavitation was discussed here a few years ago, and it was concluded that it is impossible to generate the required vacuum with a filter pump.
Now as for the bubbles, make sure that no airstone is near the inlet, hose connections are tight, and lube all o-rings with silicone grease. That should take care of it.
HarleyK
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Cavitation was discussed here a few years ago, and it was concluded that it is impossible to generate the required vacuum with a filter pump.
Now as for the bubbles, make sure that no airstone is near the inlet, hose connections are tight, and lube all o-rings with silicone grease. That should take care of it.
HarleyK
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I remembered reading this thread last week and then, as bad luck would have it, one of my fx5s began doing the micro bubble thing. I replaced the blue pad and all was good for about a week. Then, it started happening again today. I discovered that the purge valve has a slow leak/bad seal and is slowly sucking air into the canister. So once again, no need to worry about cavitaion...just check your o-rings and valves.
