Green and black mildew on lanai
 

I have a SW facing lanai with a hot tub in it and a courtyard wall behind it. I powerwash it twice a year but very quickly I get green and black mildew buildup on the cement floor, especially around the hot tub all the way to the lanai screens and on the back of the house. Does anyone know of anything I can do to keep this from happening? Anything to wash with to keep this from happening? Keep in mind I have a cat and dog that go out there so I have to be careful with chemicals.
Thanks

Interesting, we have a south facing lanai, with hot tub and cat, and NO mold. One difference, our floor has the cool step(?) coating and then a matching paint(?) same color as the house. When we moved the hot tub after about 16-18 months, there was minor staining under and around the tub. This was due to water dripping off the top when it was opened, and from bathers when they got out, and was expected.
The mold would suggest that the area is wet/damp for an extended period. Can you check for a small leak from the hot tub? You may need to drain, and move or raise the tub for a suitable inspection. You may be able to remove all of the side panels and inspect the wooden bottom of the hot tub for a leak.
I am sure if you do a Google search for pet friendly mold removal, you will find suitable products, but I am not sure this is going to solve your original problem.

Hope this helps.

I get black mold around the ring on inside of the hot tub and on the inside top of my hot tub cover. I occasionally spray it with a little bleach to rid myself of the black mold. The mold just fades away. I also spray the inside top of the hot tub cover with some diluted bleach water to prevent mold from coming. I repeat this process a few times a year.

Thanks for the information!

There is a product called JOMAX that is mixed with bleach and water. It eliminates the problem of bleach harming adjacent plants, and leaves a film of mildewicide that lasts quite a while. Spray on, let it work for a few minutes, power wash or agitate with a brush and rinse. I have used it with great success. You can but it at Home Depot, and possibly Ace.