Andrew
I also lost my first spawn of six fry over a two week period, one fry was found dead every couple of days, they were in still in the parents tank in the hatcher.
These fry were dieing, while in the same tank, the father was hatching new fry
I knew the male was sitting on more eggs (seen the female in his cave), so i moved some fish from a tank so that i had a mature tank for the fry and put the fry straight into it when they appeared out of the males cave (i have been lucky so far in that the fry are appearing fully devolped).
I also added a Fluval 2 with some polyfilter in it to the tank to help with water quality in the early days and i am giving the tank daily 50% water changes.
I have very soft water, a KH of zero & GH of zero, the ph settles just below 7 after a day or so in a storage tank, my water is full of phosphates which must be used by the water authority to buffer my tap water.
I am also adding some bi-carbonate & epsom salts to the water (in a storage tank) to slowly get the kh up to 3 and the gh up a bit, and so far (two weeks) the new batch seem fine, though still early days.
Probably better to raise your kh a bit, soft water is ideal for egg hatching, but slightly harder water is better fry rearing, can't remember the exact explanation, but even if it is just to stop any ph swings, personally think it is better.
