Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Not recommended for spas

I bought this for a 7' hot tub (mid-large tub). The adjustment mechanism on the bottom is not effective to control concentration in a spa. Specifically, I have reduced to 1 chlorine tablet in the floater and completely closed the vents yet my chlorine concentration goes high. This is a large floater. I'm sure it's fine for a pool but it's advertised as a 'pool and spa' floater which is why I bought it. I cannot recommend this for spas.