Treating White Spot Correctly ?

[Rio]

Hello everyone,
Just joined this forum today as I got my first tropical fish tank a month ago.
Everything has been good until a week ago when I got 8 female guppies. About 5 hours after I got them, I noticed that one had white spot. So I isolated her. A couple of hours later, the other three from the same tank, started to show symptoms too. So I isolated them.
Over night, three of them died and the last one was looking bad, very flaky and also had fin rot. I took them back to the shop and was told that it was my water quality that caused it. My ammonia had been 0 but when I tested it after I noticed the white spot, it was at 0.25.
The guy at the shop said NOT to treat the tank for white spot, so I didn't.

Today I did a water change and afterwards noticed that one female guppy had a couple of white spots on her. Now another has it too.
I've used Interpet anti white spot but just want to know if there is anything else I can do ? I can't find a specific answer, they all seem to be different !

Any help will be great, I'm really nervous for my poor fish. It sounds as if I haven't done my homework, sort advice and have rushed into getting a tank but it's all just gone out of my head. Trying not to panic.

Tank size: 200L
pH: 7.6
ammonia: 0.25 ppm
nitrite: 0
nitrate: 0
tank temp: 26'

Fish Symptoms : tiny white grains and flicking at gravel on one female guppy, other female has a white spot on her.

Volume and Frequency of water changes: 10% every week, I was told this was enough, is that correct ?

Chemical Additives or Media in your tank: I treat the water with Nutrafin Aqua plus, Cycle and Waste control

Tank inhabitants:
6 Mollies
8 Guppies

Recent additions to your tank (living or decoration): 8 female guppies a week ago, 3 passed away and one left living had itch spot

Exposure to chemicals: Nope

Digital photo (include if possible): Can't get a non blurred photo I'm afraid

 

[Rio]

The mollies seem a bit stressed, rapid gill movement, but they are still moving around the tank. Anything I can do to try and relieve their stress ? I've got the lights off but have got the maximum oxygenation because the instructions on the treatment says it can take the oxygen out of the water.

 

[Rio]

The Mollies look a lot happier this morning now.
I'm going to put their plastic plants and rocks back in today, instructions said to take them out because the treatment will stain them, but surely the white spot could be on the decorations ?

I'm going to test the water now. The instructions said to treat again in 4 days time and then do a 30% water change. I was going to do a 10% water change today, should I leave that for now ?

Sorry about all the questions, I just can't seem to get a straight answer.

 

[happyfuntime]

I'm not an expert but, i would treat as on package instructions and dont change water today wait till 4 days. Also stay out of the tank, ur hand and moving decorations around r stressful to the fish..... Let them rest. Increase water temp to increase speed of ich life cycle, as only the free swimming stage is affectted by meds. Good luck. I hope someone more knowledgable than I will answer u soon