You are adding WAY too much stuff to the water.
pH equalizer - completely unnecessary and swings the pH as it brings it to 7.0, then it will move towards the normal level then back to 7.0 and the yo-yo continues. What's the pH from the tap after sitting 24 hours?
stress zyme+ - an necessary additive that really isn't helping your fish.
fungus guard - do you have a fish with a fungus issue?
parasite guard - Other than the ich, are you dealing with another parasite issue?
ick guard - You have ich. That needs to be dealt with.
Based on the fish you have (pleco) you can't add salt to the tank to deal with the ich.
A stable pH of 7.6 is just fine for these fish. So, don't fiddle with that. Get your own test kit so that you don't need to rely on the LFS for that.
Your options are actually fairly simple. 1 - deal with the ich issue, and ONLY the ich issue. Other than that, you need to keep the water as clean as possible and the other issues will take care of themselves. People like to medicate because it seems like the best course of action for the fish, but many times, just keeping the water clean is all they need. They can handle many parasites, fungi, etc. if they are kept in clean water.
You have an ammonia problem still, so water changes will need to happen, WHILE medicating the fish. Here's what I suggest:
Do another 90% water change. Yup. Water changes will be a regular part of your life, and the more water you remove the better for three reasons:
- You will get rid of the extraneous chemicals in the water - far too many things going on there, if you ask me.
- Vacuum the substrate as you are doing the water change. This will remove some of the trophants (cyst-like thing I was mentioning earlier) from the substrate so that they can't multiply into more parasites - the more you remove the less there will be to kill with the medicine and the more effective the meds will be on the few that remain.
- Remove as much of the ammonia and nitrite that you are dealing with from the water - and will help the fish's nature ability to fight against the issues themselves.
Increase the temp of the tank to 82F - do this via the water change... Add the new water at 82F, and this will speed up the life cycle of the ich parasite, and shorten the treatment time. Also, increasing the temp will help the bacteria develop - the grow better at higher temps. So, this will actually help with TWO problems.
Increase surface agitation to increase oxygen levels in the water - again, this will kill two birds with one stone. Higher temps and meds in the water reduces the amount of oxygen in the water. But increasing surface agitation will increase the oxygen diffusion rate into the water and help the fish breathe easier.
Daily water changes of 90%, with increased attention to gravel vacs. - This is CONTRARY to the directions on the ich meds, which say to leave it be for a while. Given the ammonia issue, you can't take that chance. Here's how to do it properly. When you remove 90% of the water, you will be removing 90% of the medicine as well, so redose the meds at 90% of the recommended value after the water change - and make sure the water is 82F. The cleaner warmer water will help the fish also deal with any secondary infections that may be happening.
Get a liquid test kit - you need to know if the ammonia is being dealt with properly. This is independent of the ich issue.
Continue the ich treatment for 4-5 days AFTER the last sign of ich is gone. Remember, just because the ich isn't visible on the fish, doesn't mean that it isn't still present in the tank as a trophont (cyst thing on the substrate) or tomite (free swimming vulnerable stage that can be killed by meds as it searches for a new host).
I understand the frustration with this entire process, and with the advice I'm giving, I can't guarantee that no more fish will die. But, it is the best course of action to save as many of them as possible. You are fighting an uphill battle, but you CAN win it. It will take some time and a fair amount of work. The good news is that if you do this, you don't need to worry about this again - because you'll know what to do.