Are your axolotls showing any signs of stress? If they are eating that is a good sign. If they are acting ok and eating then there is probably not much to worry about. What are your water parameters too? Do you have a reading before you put the sand in? If so can you post both to see if anything has changed in your water from adding the sand. I know sand tends to increase my PH when I put some in.
Also, how cloudy is your water and is it getting less cloudy? It could be the type of sand... but if you have washed it enough it should be clear enough. My tank goes cloudy after I clean it and settles after a few hours. Cloudiness can also be due to your tank cycling. Has your tank been cycled prior to putting your axolotls in? However, it is probably not that though as you say the cloudiness came soon after you put the sand in.
Anyway, keep running your filter as that will help too. But I think there isn't really a reason for your sand to cause the water to go cloudy if you have washed it enough... I use similar hardware sand from the same shop and know many people who use sand in their aquariums with no hassles... but can't remember how many types of sand there are at Bunnings so might be wrong on that. Take it out and wash it some more and see how you go. Also do 20% water changes each day until it is clear. But yea, it should settle over a few days. If you are worried about your axolotls in the mean time, take them out and put them into a container with fresh dechlorinated water and do 100% water changes until you are happy with the state of your tank. Anyway, sand is much better than gravel so it is good you have changed.
In regards to the water clear solution, I am not really familiar with that and was unable to find a list of ingredients for that product you posted on the internet or a reference to it here... usually I am doubtful about products like that as often they aren't very useful (like Cycle and stuff like that) and pet shops recommend them to make money. However as I don't know the one you mention I will withhold judgement.

Maybe you could take some of the cloudy water and test the Accu Clear on it first? See if it works... and maybe test that water to make sure it hasn't got anything weird in it that will alter PH/ammonia, etc.