Problem with popular Algae solutions, raising pH, and my barbs being affected. Help!

[EllenAliciaJordanScusa]

My question comes down to which one of these is raising my pH levels and taking out my Barbs.
1. API CO2 Booster
2. API Algaefix
I have used both as directed and for about 10 days now.
I told my story below in case you want to know what exactly is going on to have me ask this question. Thank you

I guess I will post this here since the entire thing that occurred was all because I was having increased algae in my tank which has never happened before, and I was trying to find ways to get rid of it. If it doesn't belong here, please let me know where I can post it. Thx.
I have a 20-inch high aquarium with wood and plants and two and now three filters as of a month ago. I always had two though. Everything has always been good on any water testing I did. I use different types of tests. Both strips and liquid. My water has been the same for the 3 years that I have had my aquarium after cycling it. Including a slightly high pH that has always been hard for me to get down to perfect. But my fish are healthy and weren't displaying any effects from it. It would be a little over 7 to about 7.5, something like that. So, a half a point over at the most. I have always had 4 nerite snails and some pest snails that I keep under control that have always kept the algae at bay. It is or was a very clean looking tank. After my angelfish died (from a head injury) I got four tiger bards. This was about a year and a half ago now. One female died right away. And then one male that was bullying I put in his own tank. After this, it has been mostly peaceful and they all have been happy and healthy ever since going on almost 2 years. I also have three Tetras and 2 Corys. I did have a couple of tetras die when I first got them.
Algae started building up more and more and it seemed like my nerites weren't doing anything anymore. They are pretty old nerites. Over 8 years. maybe they don't eat as much when they are old. I don't know. I got a few more plants amazon swords I think they are called. Because I only had one type of plant and they were also not doing very well. I read that the algae competes with the plants in the tank. And the algae was probably winning. So, I read I could get some Co2 Booster to help the plants get stronger and this in return would make it harder for the algae to get what they needed. Therefore, making the algae less. I should have done this separately looking back but a couple of days after using the Co2 Booster I also started using some Algaefix. So, I did both. Both of these are API brands. For a week nothing happened. The water testing showed everything was the same as it had always been. Then I noticed my male barb acting unusual. Almost spooked, and darting a bit. Reminded me of having too much ammonia or nitrites in the water. But there wasn't. No nitrites. I did a 20% water change anyway.
I went back into the room to check on him the next day and I thought he was dead. He was upside down on the bottom barely breathing. I instantly tested my water, and it still showed no difference from before. But still having unfavorable pH I did another water change. I also added a pH neutralizer. I knew it had to be either one of the solutions I was using or the Ph doing this. I thought it was either the booster or the Algaefix. However, when I added the neutralizer, he went back to normal just about. It was nearly instantaneous. My other fish in the tank weren't affected in the slightest.
The next day he was fine. I did another water change and added a bit more of the neutralizer. The day after that though he was dead. And then one day later my female started to display the same symptoms my male barb did in the beginning and I knew it was now affecting her. The day after she too was upside down on the bottom. I checked the ph again and this time it had elevated to an 8. I knew at this point one of them must be affecting the Ph. But which one? Or is it both? So, I did all the things I did for my male. Water change and Ph neutralizer. And sure enough, she turned back over and began to swim. So far, my tetras are still fine and so are my cory catfish. Two snails, however, are at the top half out of the water which is telling. One of them is a racer nerite and he never does that. It has to be one of these because nothing else has changed. The Co2 Booster or the Algaefix from API. I decided I am not going to use anymore. But I still need to know what is going on. I can't seem to get my pH down anymore from where it is at right now which is a 7.65. Do you guys think it is the pH or one of the solutions I was putting in? Or both? What can I do for my female barb right now? And I still need to know what is going on with my algae issue. What can I do? And why after all this time am I having trouble with it? By the way, the Algaefix did a little something at first to help decrease the algae but that was it. It helped to a certain point and then stopped. It won't help any further. I don't think the Co2 Booster did anything. I used them for about 10 days. Oh, and I think I have at least two different types of Algae. Attacking my plants, glass, filters etc. But not in the water. The water is clear. It has been mostly a dark green/brown alga (looks nearly black) and now I see a new bright blue-green algae.
Thx so much and sorry it is so long.

 

[GaryE]

Personally, I would discontinue all the treatments (algae treatments are dangerous) and do a series of 40 percent water changes. I would look at feeding and lighting, the usual culprits for algae, and try to adjust without products. More water changes, less light and less food would be my starting point.

I wonder if the summer warmth combined with the unnecessary chemicals caused an oxygen drop? Algicides are known to sometimes cause that, and July is another contributor in many places.

 

[EllenAliciaJordanScusa]

Thx, Yeah I already stopped everything. But my female Barb died anyway. Exactly 2 days after first beginning symptoms exactly like the male Barb. What is strange though is the Tetras are not affected and they are the ones that are and have always been more sensitive to pH levels , temperature changes, and whatever else. More so than my Barbs for sure. And my Corydoras are fine too. And if it was an oxygen drop all of the fishes would have been affected you would think. I already had been doing the water changes, lower light, and less food and it wasn't helping. The algae was growing rapidly and killing my plants and the harder I tried the worse it got. And I remember about 7 months ago or so putting a little bit of algae stuff that I had on hand to help with algae and it didn't hurt my fish. I didn't have a problem with algae but I would do that once in a while if I thought my plants weren't getting the attention they needed. Since, it is harder for the snails to go on thin leaves. And this stuff helped with that. It was a different brand though and I can't remember the name of it. But when I used that everything was fine. But I feel like I did basically the same thing (maybe a little more and for a few more days) this time ending in completely different results. Unless, it is all just a coincidence and the Barbs died from something else.
Now, I guess from the Algaefix or from what I have been doing trying to try and lesson the algae, or both, the dark brown algae that was gooping on the filters where the water comes out and sitting on my plant leaves in layers of almost black is a lot less. But now, there is a new algae color beginning to take over. It is a light bright almost neon green color. I think what they call blue green algae. I never had either of these types of algae before. I hate it. And I really want to know what is going on with my snails. They are doing nothing about it.

 

[EllenAliciaJordanScusa]

Oh, and I wanted to correct one thing. I said I was using the Algaefix for 10 days, but you don't actually put any in every day. I had it for 10 days. It is every three days that you put a very small amount in your tank. So, I had used I believe it was 3 times.