Ok so i had postedTheLFS employee said it may be a bacterial infection. The glowfishes gills now look puffy and white. Also i know notice on my male swordtail and a Black fin tetra white spots. Maybe 3-6 total on each. Im assuming this is ick. One of the Swordtail fry dies Monday from what i thought was clamped fin but since there is like a white "tissue" substance on the tail thinks it could be fin rot. All my other fish "seem" fine. No signs of an illness.
Ok so here are the states again.
As of Monday
AMmo- 0
Nitrate- ppm
Nitrites- 0
Phos- 0 or not readable
Ph- 6.2-.4
Temp stays around 76-78
I dose once a week with flourish.
Just started using seachem replenish since i use RO/DI water and dosed mL yesterday.
have diy co2, about 1bbl per sec.
Not sure if needed but 72 watts of light on for 9 hrs over a 20 gal tank.
Ok so the LFS recommended seachem alkaline buffer to raise ph to an appropriate level. Stated should be at 7ph. ALso for the bacterial inf on the glowlight, what i think is ick, fin rot on the ST fry they gave me seachems paragaurd. They stated this will work for fin rot, ick and any bacterial infections.

Question is should i remove the fish that are sick and just trat that ffish or can i treat the whole tank. I think to treat the whole tank as i can kill any parasites that could be in the tank but not the fish. Also how do i go about using the alkaline buffer and not cause any more problems. How do i introduce it slowly so they adjust rather than get a shock.

One last thing, this is there diet. I feed them tetra baby shrimp (usually 1x week), tetra blood worms (1-2x /week), tetra flakes, tetra color bites and omega one super color small pellets as their main diet. I use the omega one, flakes and color bites mostly and give the shrimp and worms only a few times a week. Anything i need to increase in feeding, change, add, remove. I was going for months with no problems then blamo...

First thing's first, STOP listening to the people at the lfs. As much as they sound like they may know what they are talking about, most have never had or taken care of a fish outside the store. And they don't do a very good job of keeping them in the store.

Stop using ph products...you don't need it and all you're doing right now is exascerbating your other problems. Was your ph tested after you had been dosing with CO2? What is your ph out of your tap? My DIY system lowered my ph 1 solid point.

Paraguard is a good med....best thing they did for you. Leave everything in the tank and treat. Some of the food you're using may/may not be the best for the fish you have (not saying one way or the other), but you are feeding such a variety it wouldn't really matter.

Jr, My ph is 6.4 as tested last night. I gave up on tap water use 100% RODI water. The 6.4 is while the CO2 has been back in the tank for the last few days. So it seems to be steady at 6.2-6.4. Ok so off the paragaurd instructions it states 5mL to every 10 gals, so i need to 10mL to my 20 gal. Ok this may sound dumb but do i just give the tank the 10ml all at once or add it over the course of a whole day. also it says use as long as signs persist so would i dose for ex. 10ml every morning (10ml today, 10ml Thursday, 10ml Friday, ect) until i see no sign and even dose say 3 days more to make sure ive killed all bacteria?

I had to top off the tank last night as it went down from evaporation and added about 1/2 gallon. I tested just the RODI water before adding it to the tank and even that water was fairly close if not on with what the tank reads.
RODI water before tank--6.4-6.6
RODI water in tank w/DIY co2---- 6.2-6.4
Is it normal for RODI water to be that low in pH?

Ok so the advice on the alkaline buffer is to not even open it and use it..? Just use the replenish and Paraguard.
GOnna sound dumb again, but from now on should i just dose the RODI water that will be used to fill the tank up from my PWC? Meaning 25% PWC =5 gallons so only dose that 5 gallons and not the whole 20 gallon. Sorry for the ?s just want to make sure i understand everything and dont casue anymore problems.

Also on the food is there one or any that i should delete and some you would recommend?

What ph is your tap? Why 100% RODI? What kh is the water in your tank? Does replenish add back gh or does it give some kh back also?

I have a RODI system and was using 100% RODI for my shrimp tank that I have been putting together and the ph had been dropping way down because there has been very little kh in the tank to hold the ph more stable. My ph is lower than on my planted tanks at the end of the lighting period with heavy dosing of CO2. The RODI water comes out of my system at 6.8, but the tank sat at 6.2 (no CO2). The point is, there is nothing to hold ph and it can continue to drop if there is no carbonate hardness (kh) in the water. This allows the water to fluctuate more freely and can be the root cause of all your problems you have been having - it will stress the fish out.

i see what your saying. i was using all RODI due to algae. I do not know the kH of the water i dont have a test for that. The replenish as far as stated does GH not carbonate. The pH of my tap is around7.6-7.8 i had to use my high test pH as the blue on the reg pH didnt look like it was close, but now that i look it looks to be in the high 7s like stated. So maybe i will do the 25 % PWC and start with 25% tap water and 75% rodi and grow as i do the water changes so it is a 25/75, 40/60. I understand what you mean now as it can go where it wants but has no buffer to keep it stable.
Any answers on the other questions posted?

It doesn't sound like ick.. U said white tissue. Ick Is just bumps. Try looking up a pic of white fungus on fush.. Looks like a little cotton puff. Easily treatable with maracyn plus

That sounds like a good plan. I would recommend if you want to play around using RODI water, which strips all kh, to get a gh/kh test kit. They sell one that is combined.

Let me go back on the other questions....

Once you get to where you want to be with the right RODI mix, you'll know what level to drain your tank to, and then also how much water of RODI to put in the tank. For now though, you are tesing to get to where you want it. Kh is best if in the 3-4 range.

On the food, I'm not the right person to ask. I buy all my food online because I believe the brands in the store aren't the best. I use young again pet food that is made with a lot of vitamin content and high in protein. The protein is all water based protein that is better used by the fish vs some that have land based proteins which the fish just kicks out very fast. All of their foods also have garlic already in it that is well known for helping fight fish disease issues.