You will need to use more than just the standard Oxidizer and Sanitizer / Algistat. I've added both a product called Ahhsome (once a month) and also Aqua Finesse tablets. Frequent addition of Oxidizer is needed also.
It shouldn't be like you are experiencing. There is a whole section of threads devoted to leaving baquacil. It does work but from many peoples testimonials, it is a huge PITA and it doesn't come cheap. I have also seen many people's conversion threads and if i ever did it myself i would drain and save myself the headache. If there are extenuating circumstances why you would have to convert the hard way, there are plenty of folks here to guide you, and previous journeys for you to read up on.It's such a relief once the pool is finally closed for the season!!!
Is that a gunite pool? Looks like it. If it is, be aware that if you DO start to encounter mold - it likes to hide in any crevices and rough areas along the sides and bottom. If it seems that the bottom appears unusually smooth and/or slippery - brush it. I think my mistake the past few days was noticing this and not acting on it. Sweeping alone often will not get enough of it. The best way is probably to use something to clear out the lines occasionally - a floc, etc. - I can't do this real easily being that my filter system does not have any sort of multi-port valve and so I cannot vacuum to waste. My pool can be (and often is) crystal clear, but yet I can still get some mold in between the tiles and so have to be vigilant about keeping all of that clean as well. It's possible to make it work with baquacil, but it is NOT a low-maintenance method by any means. Hate to refer to it as a sort of constant 'battle', but that is essentially the case. You keep it (the water mold) in check, you don't get rid of it entirely - at least I've never been able to.Agree that it hasn’t been cheap but it also hasn’t been too difficult (so far). Right now the water is looking crystal clear (see image below). Maybe the sand filter does help? Currently my biggest issue is testing. The strips are too imprecise for me. Would you mind giving me the names of the kits you use?