Just thought I would do an update;
It was clearly a mistake cycling the tank with our hard tap water. note to self, start as you plan to run it normally. I suspect the substrate absorbed some of thee hardness from the water and then when I was using RO water plus GH+ it started with good parameters but then it went wild within days. This meant I lot of the original shrimps and I was at the point of giving up. The plants grew fine, too fine and the snails are way too numerous - I will get some assassin snails at some point. Parameters now sit at PH 5, TDS 140(ish), GH 5, KH 1, but I will keep a close eye on these.
Everything has settled nicely now (past 2 months) and the parameters are steady now and I have a dozen mixed shrimps of the originals that look healthy and happy, acting normal anyway. I am hoping to get 10 other assorted RED shrimp later this week as it is now warrm enough overnight that they can be drip acclimated overnight! I removed one of the plants and will have to trim the otther but otherwise I am happy enoigh with the setup. I will get some photos later in the week, probably when the shrimp arrive???
A bit depressing looking at the old pictures earlier in this thread and realising how many beautiful shrimp I have lost, but I am at least quite sure all is well now so will try a few more this summer. Also the floating weed which I really liked has all gone, maybe it prefers harder water, but it was a bit of a pain anyway as it was always in the way when trying to do the usual tegular tank maintenance?