Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Warm some water in a pot and dissolve in it as much salt as you can.
Wet a cloth in this water, then add dry salt to the cloth.
The dry salt is abrasive, and will remove dried, stuck-on algae. The strong salt water solution on the cloth will kill many fresh water organisms.
After a good rinse any lingering trace of salt is not a problem for even the most sensitive fresh water fish and plants.
Hard water stains. Mineral build up:
Wet the area with lemon juice.
Sprinkle on Citric Acid (sold in the grocery store as "Sour Salt")
Keep it damp with a paper towel soaked in lemon juice.
About every 15 minutes try removing the minerals, then repeat the citric acid and lemon juice application.
Other acidic material to help with minerals:
Cola, try any sort of soda pop, but Coke or Pepsi are supposed to work best.
I had some Shasta Cola that was not as good as Citric Acid and Lemon Juice method.
Vinegar was even worse. Did not do a good job at all.
I used all the same way:
Pour it on, keep it wet with paper towel soaked in that product. Return every 15 minutes to scrape loose whatever would budge, then re-apply the product.