Here is a great read re BBA.
https://fishlab.com/black-beard-algae/ You will notice, there is no mention of ozone anywhere.
My point is simple. There is more to adding things to a tank than how they might work when they are done right or when the equipment works properly. People will often use two smaller filters or two smaller heaters on a tank as a fail-safe. If one of them breaks, it doesn't mean you have 0 working as a result.
Consider two tanks one with a decent load of live plants and the other with artificial plants. Both tanks are healthy and established. And then the lone filter in each tanks dies. The one with the plants will be in a lot better shape in 24 hours than the one without them. That is because the plants can also remove ammonia and create oxygen.
I almost always run two heaters in tanks. But in those tank where I am working with plecos which cost anywhere from $100 to over $500 each, I also use an external temperature controller. I want extra protection from boiling the fish from a heater malfunction, something that I have experienced twice before.
With ozone the resulting issues if it goes wrong can be fatal. Too much will be for sure. But if the system stops working one will not have the proper nitrifying bacteria in the tank to take over. The ozone will remove some ammonia and almost all nitrite. This means one's tank will be short of ammonia oxidizers and almost devoid of the nitrite ones.
I have watched newbies getting confused about doing a fishless cycle despite having very clear step by step directions. They simply misunderstand everything which leads to mistakes and crashed cycles or ones which take forever. But no fish are harmed by this. However, a mistake with ozone is very different. We can easily measure the amount of the nitrogen compounds in our water and detect problems before they get bad. How easy is it to measure ozone in the water? Got about $75- 80 (delivered)? here is a test for ozone:
https://www.oxidationtech.com/products/ozone-monitors/dissolved-meters/k-7404.html You can get 30 more test ampules for about $1 each.
Unnlike cycling issues, once a tank is established, we normally do not need to monitor ammonia etc. regularly. We tend to check these things if we suspect something is wrong and we need to eliminate the obvious. But if running ozone into a tank you need to be more alert. There is less time to detect an issue if something goes wrong, and it is likely to be fatal a lot faster.
One last set of observations based on personal experience with BBA aside from fluctuating CO2 levels.
1. It is most likely to start on the slower growing plants.
2. It is most likely to start on plant leaves closest to the surface as they get the most light. This is especially common when one gets very tall anubias for example. The are slow growing and when they get tall, they get much more light.
3. Excess nutrients which promote BBA are likely the result of over feeding or over or under fertilizing and especially poor from tank maint.
4. BBA becomes more likely as one increases the light levels in a tank. I rarely get BBA in my lower light and easy plant tanks.
