One of the solutions that I've seen online is to starve the hydra out in a shrimp tank by not feeding the shrimp and having the shrimp eat algae only, but I was already doing that when the hydra appeared. Chemical solutions involve a series of dosing and water changes, but I am not going to be around to do that, and am afraid that I will face a hydra explosion if I wait until I return. Maybe if I dose the tank once and do a water change I can slow the population growth, but there are a number of tiny rams horn snails in the tank that would probably be killed from the treatment and would lead to an ammonia spike, and I won't be around to do a water change. I'm not new to the hobby, I've had a 55 gallon planted tank for over 35 years, but just now decided that I wanted a shrimp tank. I have NEVER had any kind of a pest problem before, other than hitch hiker snails that I dealt with by adding assassin snails, so I am totally out of my comfort zone!