Funny thing happened to me...

[johninfrance]

I added an external water filter to my 80 gallon tank yesterday. There happened to be a recent snall attack and they had been quickly multiplying and generally creeping around in spite of my best efforts to reduce their numbers (by hand).

I turned the newly added water filter on, and that night I noticed tens of snails were crawling up the tank's walls. They seem to be exoding to another promised land.

After several scoops, they got their wish, but I was wondering why more water movement made then flee ???

[tyrancooper]

I'm not exactly sure, but I've noticed the same phenomenon in my 10 gallon "kribensis grow-out" tank. I have a population of Malaysian snails in this tank that scramble towards the surface whenever I do a water change. That is how I keep the population under control.

Tyra

[johninfrance]

... and now there are no more snails in the tank ...

[DarkDiscus]

Question:

Did you both turn the tank lights off at some point during the filter change/water changes? They might think it's night time and are coming out to do their thing...

That's about all I can think of.

John

[BLUEKNIGHT]

I notice them do this after the water change. They only do it if you dont add any chlorine remover to the water.

[johninfrance]

I made my water change early in the day, so I don't think that was it. The lights were out, but it wasn't just a couple of snails, the particular thing was that ALL of the snails, big and small, began crawling and I went from a fairly snail-infested tank to none at all !

[Fish_Fin-atic]

I agree with Blueknight on this one. If the water you're using for waterchanges has even the slightest bit of Chlorine in it, the snails will die unless they can get out of the water fast. This means running (or crawling) for their lives, and the only way to go is up.
I think that snails are a great water quality indicator. If they're healthy and crawling around doing their thing, then everything is probably fine with your water. If they're lethargic, or curled in their shells at the bottom, or worse, if they're all exiting the water at the top of the tank, then there's a problem, and you should fix it quick before the fish start to feel the effects. The only time snails become a problem is when there's too many, or if you want to breed your fish. Snails will make short work of the fish eggs at night when the fish can't protect the batch. I've actually lost a few egg batches to snails in broad daylight, because the parents didn't recognise the snail as a threat (they move so slowly, and the eggs just start to dissapear). If you want to get rid of the snails, just put a peice of cucumber in the water. In a couple of hours it will be plastered with snails which you can then remove along with the peice of cucumber (Martha Stewart tip: this makes a nice tasty escargot salad for the inlaws!) ;D

[johninfrance]

The water was RO, so I don't think that was it. BUT, even though I rinsed carefully the new water filter and filtrants, maybe it was something to do with that...