Im at a loss. Not only doesn't my Cheato grow, but my nitrates are high...with no fish in my tank.
You've got a weird situation there. Why run chaeto in a tank with no fish? Are you specifically trying to grow chaeto for sale or something? It really shouldn't even be necessary in a system without fish....I duno how it would ever get enough nutrients to grow.
FYI, lack of phosphates in the water is still the problem. If you don't already have a thread tracking your tank/issue you should make one and link it here and/or PM it to me.