Heya,
i would be carefull with going to high in humidity. What it did for me two times so far was catching parasites. I think around 60% should be good for them. I cover 3/4 of the aquarium with glas, to keep the temperature up and the moisture not too high. More important is keeping the soil moist, i never let it get completely dry. I made that mistake at first and it resultet in massive worker death. Dry soil might result in the workers biting off each others abdomens. When this occured with me, i changed the soil i was using (gravel) to a substrate that would keep the moisture, and from then on the colony grew.
As for the Ytong, a good rule seems to add water as long as there is no moisture condensating on the glas. I also offer them a testing tube with water, if there are ants taking water from it, i know i need to water the ytong. A very cheap moisture indicator
Is this your main discussion thread? If so,please let us know how the colony is doing:) If i can be of any more assistance, let me know. Watch out not to have too many soldiers in the colony, they need feeding from the workers and that way "take away" food from the queens and larva. Whenever my colony seemed to go downhill and there was a high percentage of soldiers, i removed some of them. A rate of 10 workers on 1 soldier seemed to be healthy. Are there any soldiers as big as the queen yet?
Greetings,
Necturus