[Dveha]

I have a black molly. He was acting normally until after Sunday when I did my first water change. Now, he hangs out in the bubble house (ornament) all the time. Even during feeding time, he is hiding. Last night, I saw him hanging out at the top of the tank next to the water heater looking like he was kissing it. He stayed there for a long time. Now, this morning he was back in the house again during feeding time.

Is he sick?

 

[spreadtoothinly]

Do you have a water testing kit? This could be explained if the water somehow changed it's composition. What water are you using? Tap, well, RO?

 

[Dveha]

Do you have a water testing kit? This could be explained if the water somehow changed it's composition. What water are you using? Tap, well, RO?

I've been using test strips, going to try a liquid test kit tonight.
I have well water, but my water runs through a culligan filtration/softner system before it reaches my tap. I used a different water conditioner on the new water I introduced to the tank during my 15% water change.

 

[Dveha]

Do you have a water testing kit? This could be explained if the water somehow changed it's composition. What water are you using? Tap, well, RO?

Thanks for your advise. I picked up a testing kit...
Water Check - Nitrites: 0; Nitratres: 0; pH: 8.2; NH3: 0.50 ppm (my tap water pH is 8.0)

What pH is best for my Molly/Platy/Guppy aquarium and how do I gradually adjust it for them?

 

[spreadtoothinly]

Water Check - Nitrites: 0; Nitratres: 0; pH: 8.2; NH3: 0.50 ppm (my tap water pH is 8.0)

NH3 is ammonia, I believe... This ammonia reading is what is causing the fish to act strangely. If you haven't I would reccomend reading about the nitrogen cycle.
At this point you are going to have to do a fish-in cycle. You will have to test ammonia every day, and change the water when necessary. I have heard to change the water when ammonia is at 1 ppm. I would say do 50% water changes.

What pH is best for my Molly/Platy/Guppy aquarium and how do I gradually adjust it for them?

We have some awesome profiles on a LOT of fish here on this site. Here are the ideal water parameters for molly's.

Medium hard to hard (10-30 dGH), basic (pH 7.5 to 8.5), temperature 21-28C/70-82F. This fish cannot survive healthily in soft or acidic water. Many sources recommend brackish water, though in its habitat the fish generally prefers freshwater. The black strain will be healthier at the warmer end of the temperature range, and most sources recommend brackish water.

You can read the entire profile here http://www.tropicalfishkeeping.com/profiles/common-molly/
So you will not have to alter your pH, as what it is right now is basically perfect! (And even if it weren't I wouldn't recommend changing it. Most fish can adapt to different pH etc, as long as it is done gradually.)
Good luck with your tank!
http://www.tropicalfishkeeping.com/profiles/common-molly/