Marine Snails - Why are they not eating the algae and only living on the underside of the tank lid?

Question

I purchased 20 marine snails last week and placed them in my marine tank. They made a mass exodus towards the top of the tank and now are all on the underside of the lid, many of them out of the water. They do not appear to be feeding on the algae or moving much. When I move any to a lower part of the tank they just move straight back up to the lid again. I am very confused! Can anyone help? Thank you

My tank has been running for about 6 months with no problems. Currently I have 3 fish, 2 shrimps and 1 hermit crab (who doesn't bother the snails) and they are all doing fine.

I have just tested my water again and the PH, Ammonia, Nitrite and Nitrate are all within the recommended levels.

Answer 1

I have three marine tanks at present. Invertebrates tend to be more sensitive to water conditions than are fish, so even though the others don't seem to be having any problems, it's always a good idea to review your water parameters first. If you have the results from any recent testing, your ammonia and nitrite should both be 0, the nitrate should be less than 20 (even lower is better), the pH between 8.2-8.4 (for fish it can be a little lower, but inverts prefer the high pH-high calcium for building their shells), the salinity 1.024-1.026, and the temperature 76-80o (ideal).

Some other possibilities are that you don't have enough water movement to circulate the water with the dissolved oxygen to the lower portions of the tank, and they're coming to the top where the oxygen is the most concentrated. And you might want to check under the rim of your tank for some algae - your lighting is also stronger nearer the top of the tank, so this is where the algae will have the best growth - you may just not see it!

And the downside to this is that not all snails will eat all types of algae - there are definite preferences among species. And ther are some things in your tank (like "red slime algae" which is actually a bacteria - see photo: http://www.sloreef.com/bojan/Cyanobacteria_files/Cyanobacteria1.jpg ) which snails prefer not to eat at all - at best they eat some of this only when it's near more desiarable species of algae, or the snails are starving. If you can find the type of algae you have in this link: http://saltcorner.com/sections/guest/algaepage/algaepage.htm you can use the number next to the name to look up the type of snails you have at the bottom of the page to see if it's one that they'll eat.

You can also help control the algae growth by controlling what it needs to survive - light and nutrients. If you don't have any corals, anemones, or marcoalgae in the tank that you're trying to keep, simply turn the lights off - without light, the problem algae won't be able to use photosynthesis to make food for itself. If you do have the other organisms, this won't be practical. You can control nutrients by making sure you aren't overfeeding, and that you're doing adequate water changes. Your nitrate levels should be under 20 (lower is even better). If you're using tapwater as your source to make up the saltwater, you might want to have yours tested - tapwater may contain nitrate and phosphate, both of which are plant (and algae) fertilizers. If this is the case, just doing water changes won't reduce your algae - it only introduces more nutrients. You may need to switch to reverse osmosis water (available at SuperWalMarts as Culligan water in self-serve stations for $0.33/gallon once you buy the refillable containers) and/or use a phosphate absorbing sponge in your filter. If this is cyanobacteria, you can also use macroalgae to compete with it for nutrients (in this case, you want to keep your lights ON). Two good macroalgaes to use are Caulerpa and Chaetomorpha, but be careful to keep them trimmed - the Caulerpa especially can overgrow your tank, and it's the new growth that takes up the nutrients.

Also, in the event that this might be cyanobacteria, see this link: http://www.wetwebmedia.com/bluegralgae.htm

Answer 2

Maybe they are half water, half land snails and like to stay out of water for a bit. OR your water could be not good enough for them - Do you have other fish or creatures living in the tank? if you dont, and havent before it will be the water.

Answer 3

i know absolutely nothing about snails,but seen your name and had a look at your question.i think its an oxygen thing?hope you get the answer but it seems to me there going higher for oxygen. good luck and,.....Cheer up! lol ;o)