For some strange reason, my fish tank water is a blue color. What would possibly be the cause of this?

Question

10 gallon tank
8 corydoras catfish
2 dwarf platy
natural slate for decoration and a live plant
20 gallon filter by Aquaclear
--haven't added any kind of chemicals or medications to the water other than a dechlorinator

Also have black moon sand for substrate, it has been in the tank for at least 6 months if not more

And there is no background on the tank.
I was changing the water and so forth yesterday, and when i took the water out of the tank, it was literally blue! So i know something has to be turning it this color, i just don't know what!

I've had this tank set up for about a year i think, i redid it last summer, replacing gravel with sand and fake decorations with slate and real plants =]

Answer 1

That does sound odd. Is this a new tank, or a new occurrance in one that's been set up for a while?

A discoloration could be due to any number of causes, and not all may be the water itself. The glass may have a slightly blue or blue-green tint, the wavelength of the lighting may make it look blue, or reflection of a blue object in the glass may cause the water to look blue.

You might also have used a conditioner or medication with a bluish tint, or something from your tank (gravel, decor, fale plats) that's leaching the color. You may also be in the beginning stages of a cyanobacteria (also called blue-green algae, although it a bacteria, not an algae) problem (see photo: http://www.aquamax.de/Shop/Artikelbilder/Zusatzbilder/Algen%20im%20Aquarium_Blaualgen%20-%20Cyanobacteria_STUG_cyano1.jpg) If you've changed or added carbon to your filter recently, dust can be present in the water that may be making a blue-gray color if it wasn't rinsed before using.

You'll have to try and eliminate possible causes one by one, and if none of these seems to do the trick, you might need to contact your water supplier to see if they are adding something that might cause this.

Answer 2

blue.....that is very strange.
what do u have in your tank?
colored gravel? maybe it is leaching into the water.
if no colored gravel or other decorations, i'd do a 1/3 water change every other day and see if it clears up.
make sure u add some sort of chemical to get rid of the chlorine.

Answer 3

Have you added any medications or other chemicals lately ,these can sometimes stain the water a blue colour.What back ground is on your tank,could it just look blue from the reflection.

Answer 4

Methylene Blue is the first thing that comes to mind. It is generally done to betta's in little cups as a matter of course.
http://www.novalek.com/kordon/methylene_blue/index.htm

Answer 5

You might be using a bad chemical that you put in it cuz sometimes the chemicals become bad after awhile!!!
=]