Also a heads up, homebase no longer stock ammonia, in fact most UK shops are not allowed to stock it since people made house hold bombs with it.I would suggest dumping the Biomature, in case there's something in it that's interfering, use Homebase Ammonia, and see if you can get some mature media as well. Tapsafe is fine as a conditioner. You could also try leaving out the FilterStart.
You can order it online from ebay, the one im using atm is a jeyes make, white bottle red cap, around £6 inc. postage.
For gawd's sake, how ridiculous? Do the Powers-That-Be really think that I will be put off making my homemade bomb if I can't get ammonia from Homebase? D'urrrr.........