In my opinion.... the biggest pest a tank can have is often it's owner.
I am as guilty as the next guy... I start a tank and I need to be doing something... even when it should just be going through a cycle. I need to go test ....and chase water parameters, often times when there is nothing in the tank.... I want... I want to achieve the perfect state.... Honestly, if I could just keep my fingers off.. and hands out of my tanks... allowing the tanks to cycle, settle and mature... I think a lot of the outbreaks I have had to deal with would never have happened. Who doesn't freak out when they see a discoloration... OMG... it is cyano. Lets roll up the sleeves and start fighting.... dosing... trying all the magic elixirs in the hobby. OMG... I have algae... How do I get rid of it... what can I dose.....etc.... All of this usually ends up killing off beneficial stuff...leaving the nasty stuff to live unchecked.... making their outbreak even worse.... It is a vicious cycle... that starts with the owner....
I hope you get my type of sarcasm here...
These glass environments are delicate and need a chance to settle in and mature. They are going to go through ugly stages. There are going to be flatworms, algae, dinoflagellates, diatoms...critters not wanted and some we should just leave alone. I fought a long... hard battle with Dinos. I was losing miserably... and then I remembered something a guy told me decades ago about fish tanks.....fresh and salt. Let them settle. Let them find a balance. Keep you hands out of the tank and let things take their course. It is hard to do...but for me, when I don't follow this advice... I spend a crap load of money on unnecessary stuff... I usually make things worse...
Yeah... I think if many of the hobbyists here actually thought long and hard about it and were honest.... they would admit too their own actions have probably created problems than most of the other pests listed....
Some of my most successful tanks... have been the tanks that I neglected while I was setting up a new tank. All I ever did with them was feed.... and make sure they were topped off with RODI. Corals grew like crazy and fish were happy as can be. I have one in my home office I am looking at right now. I haven't done anything to it in two years....other than feed.... top off.... I cant even remember when I last did a water change to it. I have LPS, some leathers and other softies that are growing like weeds. The fish are happy, healthy... colorful.... I cant tell you when I last tested the water parameters.... It is not the most beautiful of tanks... but it is healthy and thriving...
So.... yeah.... I think the biggest pest a tank can have is often it's owner....
