Welcome to AC! Sorry to say, Bob is right, your tank is completely inadequate for the fish you have. Clown Triggers will easily exceed a foot in captivity, and I have personally cared for a Tesselata that was about 4'-4'5' long. Minimum tank size for a fish the size of a Clown is about a 180/210. While the Eel at that size would also be quite comfortable in that tank, and perhaps one even a bit smaller if properly scaped, max size is listed at 3 METERS! Add two zeros to your current tank and we'll talk! And none of these calculations take into account the extreme aggressiveness of both fish. Clown Triggers are the poster child for a fish which lives peacebly in a stable community for years, and then goes postal, killing half its tankmates overnight. And long term stable communities don't normally exist around captive Tesselates, beccause they tend to kill and eat anything that moves before it becomes a member of a community. And let me tell you, cleaning a tank which contained nothing but that aforementioned Eel required my undivided attention any time any part of my body was with a few inches of the water. If I stuck my hand in the tank, closed my eyes and tried counting to 100 I'd have never made it past 50. Perhaps your pain tolerance is higher than mine though! You really need to rethink your stocking. They're both really cool looking fish, but you're not doing right by them. But none of this addresses your problem at hand. One thing you need to learn right away is that when discussing water parameters around here, adjectives are not welcome! Numbers on the other hand...... In any case it never hurts to change 25%-33% on a fish only tank, and after a regurgitated meal it's a really good idea. But really, getting the water parameters up will be very helpful.