The ONLY way of getting rid of pest snails in ALL kinds of setup is using 'Flubenol 15'.
[update:]Sadly now, 'Flubenol 15' not available any more, but a Flubenol based product is however available, called ‘Wormer Plus’, see:
http/www.aquaessentials.co.uk/index.php?...products_id=140
I speak from experience as I have the most awkward setup for dealing with them, i.e. a SMALL Jewel Rekord tank planted with fish AND shrimp.
If you have a Juwel tank with the internal filter then the snails will also be infested into the media sponges themselves and no amount of snail chomping fish will rid a tank of them simply because they cannot get at them to eat them. Secondly they don't eat the eggs: If you have a small tank or are currently fully stocked then you can't use them anyway.
Flubenol is NOT based on copper & the added advantage of this is that it is safe with inverts (i.e. shrimp) & crusts, and is also safe with fish, plants and filter bacteria. It is nigh on impossible to overdose as it is OK up to 10 times over the recommenced dosage.
Now, it won't kill the eggs, so when getting some, £3.50's worth for a sachet of 4 grams, is enough for a ONE off treatment of 100 UK Gallons.
Divide 4 grams into 5 equal parts and store separately (this means that 1 order of 4 grams can treat up to a 20 UK Gallon tank). Then once a week AFTER your usual water change (for now & then for 4 weeks thereafter) pour some into your tank after mixing it in a mug of tank water (the tank water will go cloudy for about an hour, but this is fine).
4 weeks later, BOSH, no more poxy snails.
You'll notice no difference in snail behaviour during the first week. (Continue to pick them out - DO NOT CRUSH THEM IN THE TANK AS THIS MAY RELEASE EGGS).
During the second week you'll notice they'll get sluggish and start congregating at the water's edge.
At the end of week 2, after usual water change, if you vac at the same time you'll notice that you are vacuuming up empty snail shells.
It will take about 3 weeks for them to totally disappear.
Keep going to be 100% sure of 100% snail eradication
EVERYWHERE in your tank.
The continual dosing will take care of any hatchlings from eggs during the dosing period.
GL
Andy
PS
The result of using this method will of course mean mass extermination of snails. When dead they will decompose which will result in the release of Ammonia. It is therefore a good idea to watch for ammonia levels. Always pick out the snails (do NOT crush them) on sight.