Has anyone ever tried to clear coat gel coat or seal gel coat to stop staining . I used a product called toonbrite on my pontoon boat
never came off and didn't turn yellow .the can says it can be used on fiberglass .whats your thoughts ?

Following this myself as well. I hate using acid to clean mineral stains. Seems like it open the gelcoat pores and the stains come back faster the more you use it. I have considered putting 303 in a pump up sprayer, but am certain it will wash off immediately and would be an expensive waste of time.

If you only use the acid where needed and quickly rinse it off, that minimizes the effect. But you're right, it still probably makes it more porous. I had very good luck with a 2-3 waxings-per-season regimen on my gelcoat with a lift-kept boat. Would wax it all the way to the keel in the Spring, before it went in the water. Two coats probably just minimized the missed spots. At the end of the season, I'd have two or three little spots where the brown stain would be on the gel. Touch them up with the FSR acid, rinse THOROUGHLY, and then wax all the way to the keel again. Repeat. Gel stayed showroom.

One season I skipped the wax in the Spring. Within 2 months, had a lot of stains. Used the FSR acid to remove the stains, 2 coats of wax, and went back to the regimen. Never had a problem again.

Wax = slower

True, but brown = who cares how fast.

It would be great to find a sprayer applied sealer/wax, as I am not chomping at the bit to wax the bottom of a 38" boat!

I know a guy who put a bubbler set up under his boat kept in fresh water. The hull doesn't look like it stays in the water at all. Clean as could be

I have a friend that does the acid /wax process and it works great but it has taken its tole over the years .

I have been using Slimy Grimy on my rack stored boat for 11 years now and have had no noticeable issues with the gel coat staining any faster or any deterioration. Even being a rack stored boat I will get yellow/brown staining. I will clean mine once mid season and then at the end of the season. I found Collonite 885 paste wax really slows down staining where it is applied on the hull. Slimy Grimy is very effective of removing staining and much safer for you and the boat than acid bottom washes. I can get slimy Grimy all over my bare hands and even get a mist of it in my eyes lungs without burning. Mix it with hot water and apply it to a dry hull for best results. https://slimygrimy.com/