<a href=showthread.php?s=&postid=15683164#post15683164 target=_blank>Originally posted</a> by boviac
Hmm. Don't think I understand. Yes, in general, shop vacs do have a ball in a chamber under the suction area such that when the liquid level in the vacuum gets near the top the ball will float upwards and shut off the vacuum. But clearly since the hose is usually connected to the side of the shop vac and thereby most likely underwater when the float has shut off the vacuum, the only way I can see it siphoning water out is if one lowered the vacuum hose end below the equivalent level of the side port to which the hose was attached. And even then only the amount of water above the side hose connection should flow back out. All this is given assuming a standard shop vac build configuration that I understand.
I'm having a hard time picturing out your setup (i.e. tank vs. vac vs. end hose elevation positioning) such that would lead to a siphon effect.
Certainly the concept of a siphon effect is something every reefkeeper learns sooner or later and especially around water change time.
I can easily see a drainage event happening when one goes to lift the shop vac with two hands into a vessel for waste and the hose lies down. Nonetheless, I don't see this as a shop vac failure but rather a lesson or two learned and shared here.
Finally, let me know if anyone has discovered a shop vac that doesn't require hearing protection to operate nearby. They all are VERY LOUD and users should wear hearing protection IMHO.
. So don't use a shop vac on a bigger volume than it is listed for. Well it did clean up the water that it dumped on the floor after I emptied the container.
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