on the top of my fish tank there is some sort of “crud” all around the top of the tank it has the texture of salt but has a funny color i imagine it is dyhytrated(sorry if spelled wrong) tank water but my tank is fresh water not salt water
Guess: just assorted minerals and chemicals from the water evaporating out of your tank… your water (which is usually treated tap-water for fresh-water tanks) has several dissolved minerals and chemicals in it, and as the water evaporates from the top of the tank, these are deposited in a ring around the tank walls…
Nothing to worry about…
BTW: Welcome!
My fresh water tank gets it too, and I’ve thought it was a combo of the minerals in the water(as Astroboy suggested) and the disolved food, being evaborated by the tank light.
That white “crud” is calcium and magnesium salts which are present in hard water. If you have a “community tank”, it’s usually recommended to keep a neutral pH. Having hard water can make changing the pH difficult and, as you noticed, leave an unattractive crust on your tank.
I had this same problem and found a solution that worked really well. I thoroughly cleaned the deposits from the tank (just scrub with water and a clean toothbrush - don’t use any kind of soap), then I got a Water Softening Pillow and added it to my filter for a couple of days. Not only have the deposits not reappeared, but my clown loach’s damaged tail (he’d gotten a fungal infection) completely healed without adding any additional medications or chemicals to the tank.
Jeg elsker dig, Thomas
So I imagine your water is somewhat on the hard side for the calacium and magnesium carbonate to be left over as the water evaporates. If the tank is heated, the water will evaporate out quicker. There is usually a higher concentration of the whitish crust around openings in the tank lid and especially in areas where the water splashes a bit - like the filter. You might also notice some light streaks if some drops of water have run down the side and evaporated (I do). I find the best way to keep the outside of the tank clean is to lightly scrub the streaks off with a bit of water and then use a little squeegy on the outside; no need to try and use glass cleaners or anything. If you do water changes frequently enough, your water level will always be topped up and less stuff will seem to accumulate… if enough time elapses between changes for the level to drop an inch or so, you’re probly not changing the water frequently enough. The brownish tinge to the crust probly comes from dissolved organics in the water. Depends on what water chemistry your fish need, but you can get softer water using rain water (if it’s clean enough), or an RO filter will take out some minerals too.
I don’t have particularly hard water here in Central Illinois (city water comes from a big lake reservoir), but I get this white stuff all the time.
The important thing is, it doesn’t hurt anything. Scrub it off if it bothers you. Sometimes vinegar helps get it off. Take the filter cover or the tank lid over to the sink to do this–don’t do it at the tank.