Newbie!!!

Fair enough, sounds like it's not tannins.
It might take a while for all the ideas and suggestions to make their way to the forum, but hang on in there.
What are your water parameters? Do you have hard or soft water? Have you tried to change the pH recently? Has anything else happened in the tank? The more information that you can give us, how ever irrelevant it may sound, the better.
 

White cloudy can also be algae, I learned recently!

If it is algae, one thing should get rid of it, but it will likely come back unless you also cure the cause. But at least you'll know if it is algae or something else.

The treatment doesn't look very nice I'm afraid. It is simply covering the entire tank with something that will block all light, turning the tank lights off and leaving the tank like that for 3 days. Don't even unwrap a corner to feed the fish; they will be fine without food for 3 days.
If it is an algae bloom - microscopic algae floating in the water - they should be gone when you remove the wrapping. If it hasn't gone, it's something else.

But even if it turns out to be something else it is worth finding a way to screen the sunlight from the tank, whether it is drawing the curtain or even using a free standing decorative screen. And if the cloudiness has gone when you unwrap the tank, you don't want it coming back, so you'll still need to stop sunlight shining on the tank.

It is worth cleaning the wood and the tank, and check the filter first.

Yes, literally block all the light. Fish can go without food for 7 to 10 days. This is why it is better to just leave them rather than use one of those holiday blocks if your holiday lasts 7 to 10 days.

The wood was in the tank before, just owned by someone else. It's an old piece.

The more I read, the more I'm thinking algae from the sunlight. I think I'll try what you said Sue.  Sorry for my stupid questions, but once I've got the tank ready, do I just tape a towel over all the sides?  Xxx

I quite agree. The only stupid question is one you don't ask 

  Are you suggesting we give stupid answers on the forum 




Mumble mumble, we all make mistakes from time to time, mumble........

Quick reply as work hectic today. NB. I haven't had time to go through all the posts in this thread, so Paddy may well be justified re a stupid answer, as I'm not sure my reply relates to the same as what you're experiencing.

I had white-coloured slime which kept appearing on my wood during its first 6-8 weeks in the tank. I scrubbed the wood every 2-3 days with a toothbrush bought specifically for fishkeeping purposes; eventually, the wood just stopped producing the slime.

I doubt she was offended

Well you are all extremely helpful to me!!!!

Don't think the wood is the problem with it being an old piece. Plus it's got green algae on it. I'm going to speak to the hubby tonight, sort the tank, then put it on lockdown for 3 days lol. Fingers crossed everyone!!! Xxx

Well like you say, it will rule it out if nothing else xxx