If you have a water test kit, go ahead and test for ammonia and nitrites, an dgive me the results in parts per million (ppm).
If you don't have one, we just need to do something. Removing 70% of the water at once is too much, and that may have killed off the good bacteria. When that happens, you end up with ammonia or nitrites at toxic levels. This is especially likely if you did the cleaning a day ago or more. The other strong possibility is the algae remover. This is more likely if you just did the cleaning today. It is toxic to fish, and is even more likely to be so when combined with other chemicals. I recommend that you remove half the water, and replace it with same temperature, StressCoat treated water. Don't add any other chemicals. What you can add is a little aquarium salt. Use one tablespoon per five gallons of water.
If these measures don't help, the fish may be suffering from pH shock. The pH gradually changes in old water and the fish adapt to it. when we add a lot of new water, there can be a rapid pH drop, which they can't adjust to. We can't know if that is what happened unless you know the pH of the old water. So, for now, go ahead and do the 50% water change, only add StressCoat, and the aquarium salt. If you have test results, let me know what they are. If you have more questions, let me know in a REPLY. I wish you success.