
Also i noticed that i have a snail in my tank. Did this come from the blood worms?
Shall i leave it in or take it out?
Please help there is nothing in books about colour changing gravel and the magic appearance of snails.
Cheers

I've got the same problem with the Alge. Its just as you describe it 'diatoms.' Although I've had it for quite some time now, several months in fact. I am starting to get a little worried about it as I have no started buying water from a shop that uses RO water. I was using tap water at first (the local water is pretty clean) then I started using bottled water, and now the Shops water.Bol said:The first thing I'd check with the gravel is, is the new brown color kind of a slimy coating, that rubs off easily?
If so, what you most likely have is an outbreak of diatoms (sometimes called 'diatom algae'). It's pretty common in newer tanks (I usually see it in my tanks about ... four to seven weeks after cycling is complete). Also happens in low-light tanks.
It's not harmful to the fish, and usually goes away without any intervention as the tank matures, in my experience. Also, otos like to munch it off of rocks and glass -- not sure about gravel, though.
About the snail, were the bloodworms live?
Also, if you put any live plants in the tank, chances are good that's where the snail came from (eggs on the plants).
A few snails can be beneficial, but too many can be a hassle, in my opinion. If you do have a couple of snails (I'm assuming they're the plain old 'pond snails'), they'll be a sure-fire indicator if you're overfeeding your fish. If you overfeed, chances are you'll fairly suddenly see that you have dozens and dozens of snails.