Vince-I haven't had any problems handling sodium hydroxide, but agree to use care with caustic chemicals. I bought my sodium hydroxide (technical grade) from Essential Depot: http://m.essentialdepot.com/site/854966 They usually run specials and free shipping. I think aptasia X is water downed kalkwasser paste ? I used it in my Red Sea Max to help with aptasia with varying success. Kris-my coraline algae will bleach from the sodium hydroxide also, but grows back.