First of all, Welcome to TRT!
On to your question, nope, a UG will not help in the way you are hoping it will,,,
To put it bluntly, you have too many(big) fish for the size tank you have, as in the parrots make a lotta mess,,,
(you never mentioned what kind of filter you have on the tank already)
I'm thinking a
canister filter would do you well,,Magnum350,Fluval etc.
if you get one, change the media often, as the bioload will be to the extreme with what you have.
Also, consider the amount /frequency you are feeding the fish,,,food in, poop out,,,, uneaten food will add to the problem,,,not to mention the waste from the fish,,,
bottom line: you have a system not capable of servicing the load in the tank,,,
up the filtration, or cut down on the feeding/number of fish in the tank,,,,(the big ones,,,)rule of thumb,,,inch of fish for gallon of water, (actual water, don't forget rocks/decorations take up space)
Again , Welcome to TRT!