Stuart....Boy a whole bunch of questions. Blackworms...........someone check me on this but they are a different worm from the old 'red tubifex'. I'm not too sure if it's OK to call them 'black tubifex' or not but a lot of people do so. In any case they about the same length as the reds, maybe a 'skooch' longer, but maybe 20% thicker and blackish....if you put them next to a red there is no doubt which is which. I've been dealing with the red variety since oh about 1968...........they are good food but they are in my opinion trouble and haven't used them since the blacks came out. The reds very dirty and begin to break down,die, very quickly. When the so called 'blacks' came out about 1980 (maybe earlier) people thought not much better of them than the reds, but now more and more people are beginning to learn how to handle these worms and the results, in my mind are just super, fantastic for breeding. Here's how I keep them. If you make a fist......that's about how much I get at a time. I put them in a circular 'tupperware' bowl with no top that is about 6-7" in diameter and maybe 6-7 inches tall. I put enough tap water in the bowl to just, just not quite cover the wiggling worms. Through experience I've found it important not to cover them completly...it just doesn't last as long if you cover them with water. Now, for the next 4-6 days I will take them out of the refrigerator and rinse them vigorously and let them settle down....15-20 seconds.....maybe 3-4 times, lower the water to just covering them and put them back in the fridge.......I'll do that 2-3 times a day. There is NO SMELL....leave the top off.....the wife won't mind after a bit. After the 4-5-6 days when the water rinses as perfectly clear then and only then do I feed them. If you time your buying you will always have some worms to feed..............now for the kicker.........how long do they stay alive you ask??? Honestly I have keept them alive with NO feeding of the worms of any sort for over a month, they don't die, I will have fed them all to the fish......rinsing twice a day even after they are clean. Folks........I think that worms. of all sorts of kinds, are a staple of our fishes. I would bet more than a nickle that worms may be as much as 50-60% of fishes diets. I can not remember a fish, except one that was all but dead, that wouldn't come 'flying from the other side of the tank to fight for a worm of any sort......white worms, micro-worm for fry, earth worms, black worms. BUT BE PATIENT UNTIL THEY"RE CLEAN!!!! Stuart........people will get tired of me talking.......yes I meant a low of 4.8. I've kept and spawned dwarfs on purpose at 4.5, and spawned discus on purpose at 5.5, and do you want to spawn wild angels.............put their water at pH-5.0-5.5 and virtually no hardness. Prices for R.O. are about 1/2 of your price.....I understand your hesitancy, But some of these dwarfs can be real 'buggers' and you'll not get any viable fry without going to some of these extremes. Sorry guys I get carried away!!!......Have a good 4th........even over there in England......;-) Mike