Sick Mollies?

Question
I have a 29 gallon tank.  I am very new at this and made the mistake of stocking it too quickly.  I have 2 swordtails, 2 dalmatian mollies and 2 black lyretail mollies.  One of the black mollies started showing signs of illness right away and was found floating but alive so I moved her to a 10 gallon tank and started treating her.  Couple of days later the male dalmatians' eyes were popping out so  move him to the treatment tank as well.  After 1 day his eyes were normal and on the second day he was picking on the still sick black molly so I moved him back to the big tank.  Now as you can probably guess my nitrite levels got a little high, up to 3.0.  Since the nitrite started rising I have been doing 20% water changes everyday.  Last night the nitrite was between 0.5 and 1.0.  So that seems to be helping but since yesterday the 2 dalmatian mollies have been laying on the bottom.  They come up to eat but other than that they just lay there.  I can't see any obvious sign of disease but since they already have white spots I can't really tell.  I was advised not to use the nitrite reducers because it might affect the growth of good bacteria.  So just water changes.  Should I move the 2 dalmatians to the "sick" tank?  Other parameters are nitrate 0, hardness 75, O chlorine, alkalinity 300, and pH 8.4. I was told the alkalinity and pH would fix itself but so far we stay on the very high end of the spectrum.  I really don't want to loose these fish.  I like them all for different reasons.  And FYI the sick lyretail molly, who I think I received sick for the store,  I believe she has tail rot.  Her tail looks as if it is shriveling up.  Also her gills look white but so do all the other fish and I cant remember if they were like that when I got them.  Thank you so much for your help.

Answer
Hi Amy:  ok... I would keep the fish where they are... both tanks are infected at this point and so we shall treat them both... moving the fish would just cause stress and that is not good when they are sick.  Raise the water temperature to about 80 degrees...but do it slowly... on degree per hour... Add aquarium salt per its label instruction... and go down to your local aquarium and get something called general cure or triple sulfate... It sounds like to me you have a lot going on in your tank... fin rot and Popeye... so a general treatment should work... you can isolate fish that are not getting better to the ten gallon tank as needed.... use the ten gallon as the ICU tank... I am concerned about your pH... that is really high... while you are at the aquarium check into getting a chemical fix for the pH... I hate to use those...but I am afraid your levels are too high. if you have not already done so add a lot of live plants... 5 or 6 or more...this will help with the bacterial levels in your tank.  We have to however identify why your pH is so high... live bearers don't mind a 7.8 pH but over 8 is an issue... Tell me about your tank decorations, and test your tap water to see what its pH is....   Lets start with this and PLEASE keep me informed ... I don't mind answering questions... dave