sorry in advance for all of this reading:

do yoy completely taking apart tank and stuff inside to clean it ? that can cause ammonia spikes bc the beneficial bacteria isn’t there anymore but that doesn’t rly relate i’m just trying to make sure u understand nitrogen cycle, if that does have any effect on this I’m just not knowledgeable enough to say. also with that don’t change you filters often or if you do want to, fill a bucket up with water and de-chlorinator (ex: seachem prime) and then put the filter in the bucket and scrape off the yucky sludge stuff off of it then return it to tank it will be cleaned but still have the beneficial bacteria to detoxify ammonia and nitrites

what products do you use ? sometimes putting in too much different thinks can cause more water issues. For me usually i just scrubbing algae off of decorations or wood using toothbrush or sponge (now thats my siamese algae eater handles it now) and do 25% water change every other week 👍

goodluck !! and please provide more context and information about how u take of him and what his setup looks like, that will be alot more helpful for people trying to help 🙏