Umm, PearlscaleFan, it is very good of you to provide the information but unfortunately, I think you have misquoted some of it. It's okay. Just file it away for future reference.
First of all, does that white spot look like a grain of salt. Not flat against the scale or skin.
It is impossible to prevent ich. However, it is most like brought in by a new fish that is already infested rather than "just happens".
The cyst drops to the gravel before releasing 100's of free swimming tomites which is the only stage that is subjectable to treatment.
You can try vacuuming the gravel to remove some cyst (remove 1 cyst is more effective than removing 100 tomites). You should change out around 30% to be effective.
Ichthyophthiriasis is a parasite and not a bacteria.
If it is treatment by salt then the tank should be kept at 0.3% concentration which is 1g/L or 1tsp/gal. Salt bath of 2-3% can be attempted if the infestion is bad. That is 4oz/gal for 3% or 30g/L. However, that is a quick salt bath as most fish will be stressed out within a minute at 3% (BTW, that is seawater concentration). It cannot be for prolonged exposure.
All treatment must be continued for 6 days after the last white spot disappeared. However, I would recommend maintaining salt for 10 days.
Only increase the temp of the tank if you have a good treatment regime happening. Because if you don't the ich will multiple like mad and then you will have a dead fish in days. There is evidence that ich will start to die off at temps above 86*F but some fish can't handle temp that high so it is a risky option.
The most important question here is, is it actually ich you are looking at? Don't jump to conclusions.
Sorry, PSfan, I'm not picking on you but it is best if we clear this up now.