Water treatments won't make the water OK for fish.
A dechlorinator just removes chlorine and usually heavy metals; chlorine kills bacteria and irritates fish so that needs to be removed and heavy metals such as copper can kill shrimps so those too need to be removed.
If you used a bacterial supplement, unless it was Dr Tim's One & Only or Tetra Safe Start, that will have done nothing to the tank as they contain the wrong species of nitrite eating bacteria. The two I mentioned do contain the correct species but Dr Tim's in hard to get in the UK and TSS doesn't always work as it is often damaged by incorrect handling between the factory and your tank.
A tank that is safe for fish has two colonies of bacteria in the filter. Even if you used Dr Tim's, without fish to feed the new colonies they will go dormant. If you did manage to find a bacterial supplement that actually worked, you could only prove it by adding ammonia to check.
What exactly do you mean by filter aid? If you have used
this all it does is clump together floating bits in the water; it doesn't make the tank safe for fish.
As for white clouds, 47cm is a bit on the short side. Do you desperately want these fish are are you open to changing your stocking short list? Other, smaller, warmer water fish would be more suitable and would leave you bigger options when it comes to things like shrimps.
You don't actually need bottom feeders. They still need to be fed, they don't just live on left overs. Cleaning the bottom of the tank is the fishkeeper's job. Bottom feeders can be an attractive addition to a tank, you should get them because you want something that lives on the bottom, not as a clean up fish/shrimp etc.
If you do really want white clouds, I would keep them alone. There are very few temperate fish for sale and fish like zebra danios need tanks at least a metre long despite their size. White clouds do come in two colours, grey and yellow (gold white clouds) so if you wanted some variety you could get a mixture.
The 10 to 12 fish you originally suggested would put you right at the tank's limit to overstocked (100% for 10, 120% for 12). I would stick with 8 maximum for a tank this size.