Cloudy

It is a bacterial bloom, very common in newly set up tanks. Unfortunately, these are not the bacteria we want to grow. Bloom bacteria feed on organic substances in the tank, and new tanks have a lot of these - chemicals in the corner sealant, plasticiser in all the new plastic things etc. They live free floating in the water, unlike the filter bacteria, and they multiply very quickly; and we can see them as the cloudiness.
The good news is that once they have eaten all the available food, they die and the water clears. It's just a matter of waiting. They won't affect the progress of the cycle, they just make he tank look a bit odd.



Your pH goes hand in hand with your hardness - both are usually high together.

Sorry to hear that your bacterial bloom hasn't cleared up yet.
Sue has indicated that it is just a matter of time befor the problem resolves itself, and as the bacteria are in the water (rather than the filter) I would have though that water changes would have helped. I guess if a food source is still available then the bacteria will multiply after the water change, so you wont see an improvement in the cloudy tank.
I had this problem with my 50L temperate tank not long after I set that up. I had upgraded some of my temperate fish to the 50L tank,  and also moved the decor and filter from the previous tank. The fish were fine for a couple of weeks, then the tank suddenly became cloudy. I was worried about the fish, and did a lot of frequent water changes, but the fish didn't seem bothered. The cloudiness disappeared after a while, as suddenly as it appeared, and I've not had any problems since.
I know this doesn't help you right know, but I hope it gives some comfort that everything will be ok eventually.

now there is a kind of white 'cotton wool' algae resting on the substrate like an early morning fog

@Lellynelly What I'm about to suggest isn't a real fix - I think that is just time that is needed, but it might help speed the clearing process. Try a flocculating additive like API Accu-clear. These cause particles (to be honest I not sure about bacteria) to collect and either fall out of the water column or be retained in the filter.
Do you have some water readings for Ammonia, Nitrite and pH and hardness? Somebody might spot something to explain what you are seeing.

Hi Matt. No For some reason my computer won't let me upload one. It says its too big and I have no idea how to shrink it. Not sure how I uploaded the first one at the beginning of this thread!

it's like cotton fibres. the water is now clear though. I am hoping to take a sample to the aquarist tomorrow and see if they can recommend something to add to get rid of it

Since you are fishless cycling you have a while yet before you get fish. Take a sample to the aquarist (shop?) by all means to see if it can be identified, but I would not add any chemicals. Two reason - it may have gone away by the time the tank is ready for fish and any chemical could interfere with the newly establishing bacteria colonies.
If it is still there when the cycle finishes, maybe add some chemical then, but wait before adding fish till the chemical has been removed, and to check that the bacteria are still OK.



Re Matt's suggestion of algae - do you have the tank lights on at all? There are no plants in the photo in an earlier post, so the lights should be off all the time to avoid algal growth.

@Lellynelly As you describe it its starting to sound rather attractive... you could be on to aquascaping's next big thing and we are trying to kill it for you...... Oops.

Can you syphon it off the substrate?

I did syphon it off but it came back.
I went to an aquarist today, took a water sample for testing and showed them a photo. After mush discussion between 3 staff members they decided it is fungus and harmless.
My plan is to syphon it up again, then I am going to add some water from one of my other aquaria to speed up the cycling.
They told me the water is fine, but the nitrates are on zero and shouldnt be. So after I've added some from another tank and syphed the fungus they said it should kick the cycle into completing so They expect it should be ready for fish in a week or two

Using water from the other tank won't do much as the bacteria we want are attached to surfaces not in the water. That's why we start with so very very few - that's all there is in our tap water.
But if you have another tank you can speed the cycle up by taking some media from the filter. This is much more effective than using water from the other tank. It is safe to remove up a third of the other tank's media, just swap a bit with the media in the new tank. You can use any type of media, and if it sponge just cut it up to make it fit.