I need help! I am new to "fishtanking"

-- My husband and I have had them over the years, but its been a LONG time, and in the old days it was just a Kaman Alligator (by himself obviously) and some piranhas (YEARS ago)...
We just got a 45 gal upright from one of his customers, with a 12" Pleco (Charlie)...I waited 2 days, everything looked good....then I added 2 Green Spotted Puffers (mistake right there...one died within a few hours and the other one 2 days ago)...oh the tank has been set up for 13 days. We now have several feeder guppies, one fancy guppy, 1 fantail
goldfish and 2 flame gouramis, and 2 ghost shrimp. All was great, but a few days ago the water got really cloudy....greenish, but its not algae on the sides...can't see through it. Except for the darned puffers, which are gone now, everyone is doing great in the tank! I use tropical flakes and granules (that aren't supposed to make it cloudy) and have been supplementing Charlie (pleco) with a couple algae wafers every other day.
Right now I just did a 50%
water change - I'm in the process of refilling it and wondered if I could just use hose water, if i use the conditioner?? I have a Top Fin 60 filter, which my husband just insisted we turn off for a couple days...

is this right? I have Top Fin Water Conditioner....(there is also a bubble wand in the tank for air bubbles).
I'm sorry to sound so amatuerish....I really want this to work and have been following this website for help on all issues...but this one has really got me baffled!! I want to add a molly and a bali shark and a couple other types of gourami's - but won't until this water is clear.
Can you recommend what additives are vital to have on hand? Money's tight, so i have to wait for Wed to get the water test kits, and then i will be able to watch it very close - but have no idea what additives i need to have on hand??
THANK YOU ALL!! I love this site!!! I put it on my FB profile!
Kathy