Your salinity is on the rise without you adding any water because of evaporation. When any water evaporates, only pure water is removed. All other substances stay in the water remaining, in other words, your salt stays in the tank, hence the rise in salinity. Plain (dechlorinated tap water or RO water) must be added to keep the salinity levels stable. How much depends on many different factors. For example, I have central air conditioning which really sucks out the water on my 55g....I have to replace approx. 1 gallon every other day. What alot of people do is to either pick out a reference point (like a certain point on an intake tube) or they put an actual mark on the outside of the tank using marker or even tape. When the water level falls below this mark, then you know you need to add freshwater to your tank.
In a 29g tank there is no way you will be able to add an ocellaris clown to a tank already containing a domino. And the tank is too small to add a larger fish either.....the only fish that would probably be alright would be one of the dottybacks. If you really want a clownfish, then you will have to take the domino back to the store. BTW, the ocellaris will be fine in a 29g....they are a small fish that stays small.....
In a 29g tank there is no way you will be able to add an ocellaris clown to a tank already containing a domino. And the tank is too small to add a larger fish either.....the only fish that would probably be alright would be one of the dottybacks. If you really want a clownfish, then you will have to take the domino back to the store. BTW, the ocellaris will be fine in a 29g....they are a small fish that stays small.....
right now things are fine because the domino is smaller and outnumbered.....