Hi mickey its good that youre researching and doing homework before impulsively buying a difficult to care for organism.
I dont intend to be harsh or anything, but im telling you what i told someone else looking for an anemone to host her clowns. Im also assuming youre new to the hobby cos you posted this in the beginners section. Do correct me if i am mistaken.
Sea anemones require high lighting (5-7watts per gallon of Power Compact or VeryHigh Output lighting in a normal depth tank.). They also need very high water quality. What lighting are you running on your 23g?
Clownfish hosting anemones tend to move around a lot, even if all parameters seem excellent. This means they will crawl over your rockwork, killing corals in the process. This occurs bu various means; by stinging them, my making them fall off the rock, by crushing them completely etc.
If you intend to get an anemone, it would have been better to introduce it first. Maybe itll settle in a place and stop moving. This is unlikely for most species of clown hosts and they move periodically forever.
If an anemone starts to die, it releases large volumes of toxins by rotting and releasing nitrites and ammonia into the tank. Most of the time this is so bad that the whole tanks water smells. By this time, corals and some fish would start dying. The aquarist most of the time finds out too late.
Most books recommend keeping anemones only to aquarists who have had at least 2years of successful reefing experience. Even then, most dont survive more than 6months.
Many anemones seem to thrive for a while and then die off for some unknown reason. Many are also drawn into powerheads and filters. Some just disappear into a crevice behind the tank with no food or light and slowly starve.
Besides, clowns are quirky creatures. They'll host anything, xenias, frogspawn, hammer, torch, and other euphyllia corals, leathers and all sorts oof stuff, even turtle grass. I once had a pair of skunks in my 6'tank. They were lonely, so i got them an anemone after 3yrs in reefs. They refused to accept it and still hung out in my tubeworm colony.
Please dont buy anemones unless youre confident you can take care of them, objectively.