Hey, I hate to be the bearer of bad news but a 50ltr tank isnt even big enough for 1 axie let alone 3! you will need a 4ft long tank! that small volume of water will not be able to cope with the waste from 3 axies and you will be constantly be running into water issues! get a bigger tank! (i had 1 axie in a 60ltr and it was waayyy too small for him! he's now in a 180ltr!)
Look up how to cycle a tank, you should ideally have it cycled for a number of weeks before adding any live animal in there as your water chemistry will be all over the place!
You need to research this in a big way! Who told you it would be okay for 3 axies in a 50ltr? whoever it is needs shooting!
My advice is to return the axies to wherever they are from untill you can provide an adequate home for them
Im seriously hoping you mean 50gal instead of 50ltr!
Im guessing from your post that you have not done your research into keeping axolotls and if thats the case I hope you havnt also made other mistakes like using gravel or a heater!
Please do reasearch as your axies will surely suffer if they are in an uncycled tank that tiny!
Everyone on here is here to help so please gather as much info as you can, to help with the cloudy water we will need to know your water parameters,
Nitrate
Nitrite
Ammonia
etc.
Please find your axies a suitable home!
(if it was a typo and you meant 50gal i apologise, if not then you have to think seriously about what you are going to do with your axies as they will not be able to live in 50ltrs of water!)
Edit: sorry feel abit harsh about the lecture as i know you are new to this, just abit shocked by the small tank size!