Toilet cleaning question?

I had this problem in an apartment I rented once. You could try one of those discs that you put in the back tank, make sure it has chlorine in it.

Easy Toilet Cleaner

Sprinkle 1/2 box of baking soda into the toilet tank once a month. Let it stand overnight before flushing. The tank and the bowl will be both clean and deodorized.

Fight mold and mildew

To remove and inhibit bathroom mold and mildew, pour a solution of 3 tablespoons white vinegar, 1 teaspoon borax, and 2 cups hot water into a clean, recycled spray bottle and give it a few good shakes. Then spray the mixture on painted surfaces, tiles, windows, or wherever you see mold or mildew spots. Use a soft scrub brush to work the solution into the stains or just let it soak in.

Disinfect toilet bowls

Want an easy way to keep your toilet looking and smelling clean? Pour 2 cups white vinegar into the bowl and let the solution soak overnight before flushing. Including this vinegar soak in your weekly cleaning regimen will also help keep away those ugly water rings that typically appear just above the water level.

sprinkle a little cleanser in the bowl and brush it down. I end up only doing this step about once a week Good Luck !

The only thing I can think of is using bleach. Pour a little in the tank and it should keep the mold from growing.

Clorox makes a tablet that you can drop in the tank of the toilet and every time you flush it gets cleaner in the bowl they work great. If you have a septic system I wouldn't use them though try the Kaboom version they work great too.

buy a bleach puck that hangs in the tank water. if your tank is black, pour 1/2 gallon or so of bleach into it before you go to bed. flush in the morning then hang the puck in it. if you have pets that drink from the toilet, be sure to keep the toilet seat lid down or the door closed

I clean my toilet once a week and never have this problem.