embillma

Have 2 Gerber 1.6 gal toilets that flush water thru holes in the underside of the elongated bowl edge. Find even with frequent cleaning ?mold? builds up and brushing causes black flakes to be loosened but openings never become completely clean.
Are there any suggestions for an additive to the tank water, or other approaches to keep the passages clean ?

majakdragon

I don't recommend any "in tank" cleaners. These seem to ruin the rubber and plastic parts. Not sure it is mold (although it could be) but you could pour bleach or 50/50 mixture of bleach and water directly into the hole located under the flapper (after turning off the supply valve and flushing). This is the route the water takes when the toilet is flushed. Let it sit for about 10 minutes and then flush. It will kill any mold. I use vinegar a couple times a year to help with calcium deposits which also form in and around these holes. Using a mirror, I check to make sure none of the holes are completely clogged and if so, a wire coat hanger can help clear them.

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CraigFL

It's probably mold. I use the big CLOROX bleach pellet in my tak to combat this. As stated, it will do damage to the rubber flapper and other parts over a long period of use but it's a small price to pay for the convenience...

embillma

Tried the Clorox pellet some months ago without success. Will give the Dragon's idea a shot; have never found any holes clogged in 12+ years, but frustration sets in.