Loaches Online Forum

I have a used 30 gallon tank which will become my hill stream tank.
I think this tank may have been a salt water tank. Is there any special cleaning procedure I should use? I've seen some other posts in the past about this but don't remember what it said.

I've never done this, but I'd just fill it with water, let it circulate for a day or two, change as much water as possible, and just repeat maybe 3-4 times. I'm sure there's better ways, but that's what I'd do.

When I bought a 60G and converted it, it was covered with gunk. I filled it with water, dumped a gallon of vinegar in, and let it soak overnight. The gunk washed right off.

Otherwise the advice of just running a LOT of water through it sounds good.

Most saltwater pathogens are killed by the freshwater, and visa-versa.

A tank run for salt is safe for re-use as a fresh water tank.
a) the minerals are not harmful, just cosmetic. Yes, they can dissolve in the water over time, making the water a tiny bit harder. So little over such a long time that hobby test kits cannot measure it.
b) Diseases and parasites of salt water do not survive in fresh water. By the time you have washed the tank, set it up and done a fishless cycle there will be no diseases or parasites to worry about.

There is the cosmetic issue of the white crusty stuff.
If all it is is salt, then the white crusty stuff comes right off. Wash it any you are done.

If it is mineral deposits that have hardened and are really stuck on then it takes more work to remove them. Soaking them in an acidic bath softens them.

I have tried the following:
1) Scrape away all I an with a razor. (Glass tank, not acrylic)
2) Soak in one of 4 liquids, maintaining the moisture by soaking a paper towel in that fluid, too and laying it on the minerals.
3) Repeat.

The 4 things I tried:

Vinegar: Not very helpful.
Soda (I think it was Shasta cola): Pretty good.
Lemon Juice: Not too bad.

And the winner is:
Rub the stuck on minerals in lemon juice, then sprinkle on citric acid crystals, sold on the spice shelf as 'Sour Salt'. Then cover with a paper towel kept wet with lemon juice. It took about 2-3 treatments, soaking for 15 minutes to 1/2 an hour between bouts with the razor.
WEAR GLOVES!

Do not use the razor on plastic parts of the tank (Hood, rim). It can cut these. Not really a serious problem, just cosmetic. Soaking in lemon juice + citric acid is safe for the plastic parts.
Be extremely careful with the razor near the silicone. I would rather leave 1/4" of minerals near the silicone than get any closer with the razor.

warm water and vinegar will help break down the salt/hard water build-up on the tank. make sure you get it really clean, and don't use any harsh solvents or else it might damage the silicon/acrylic.

Since it seems that acids are key in cleaning salts and or calciferous algae - I have to ask if anyone has used a dilute solution of Muriatic acid? Normally i'd just go with Vinegar, but since I've got a couple gallons of pool acid already...

I figure letting the tank soak filled with water with a pH of around 2-3 ought to the trick, and be the lazy man's way of cleaning an acrylic tank.

Thoughts?

Muriatic acid will work just fine. It is so strong that I generally do not suggest a novice simply go buy some and go to town on their tank.
If you know how to handle it, safety gear, disposal... go for it.