I'm very sorry to hear that.
I hope it's okay to respond to your post here but I'll keep your e-mail on hand too just in case this post gets banned. I've reread the forum rules and believe this post will be okay as it is on topic about panda loss.
I had lost one more panda since I posted last and have only 3 remaining. The LFS no longer stocks pandas at all, not that I was planning on restocking from them anyway--frankly I'm thrilled with my tank and inhabitants as-is.
I'll never be sure, but I can only guess it was a nitrite spike that got the poor panda, after I'd tried eradicating a benign fungus (came in on some plants) with a tablet from Jungle Buddies. The tablet threw my bio filter off for about a week and that was enough to kill the panda off, even though the readings weren't too bad and my other fish were not affected. Still, it was the only parameter out of whack & after I realized that the tablet was hard on biological filters, I had almost braced myself for a loss. Fortunately it was not a major hit to my bio-filter and the filter re-established quickly--plus once I realized I'd lost some biological capacity, I quickly took the following steps to minimize the damage while the filter recovered.
I've found a very interesting product called Chemi Pure by Boyd's. I can only describe it as black gunk in a filter bag--just stick it in the filter, put some floss media around it, and you're good to go. I ordered it online and it's available at many internet retailers--don't know if it's available in the UK. I don't really understand what it is, but after reading what it supposedly does, I decided to try it. It's not a miracle cure--if for example you have a nitrite or ammonia spike from a dead fish--which I did after the last panda died and I hadn't found him for a few days--well you're going to have a spike and that's that. The Chemi Pure can take the edge off, though.
What really helped was that I used Nitra-Zorb packet in my Ecco Cannister filter to take up the excess ammonia and nitrites while my bio-filter re-established itself. NitraZorb is another chemical filter media that is very easy to use and is even rechargeable in salt water. I was introduced to it when I was using the Rena XP3 Filter, because the same company that makes the filter, makes the Nitra-Zorb. It works very well either to help in emergencies or to take the edge off of unexpected ammonia spikes from dead fish, food that got hidden somewhere to rot, that sort of thing.
Getting back to Chemi-Pure--it seems to help keep nitrates down, and the water is extraordinarily clear and my Danios all of a sudden just GREWWWW. They hadn't grown much since I got them around last fall but after adding Chemi-Pure to my filter, the Danios grew, the green Aeneus that had looked kind of iffy perked right up, and the 3 surviving pandas are looking very panda-ish. I don't believe that Chemi-Pure's assistance lies in what it filters out--rather it seems to put something back into the system, but I I am not sure I have the education to understand what.
I've also recently added many more plants, 2 huge arches of Malaysian Driftwood, one small piece of Malaysian Driftwood, and a new powerful CoraLife single strip compact flurosecent light fixture to further upgrade my main tank. It's finally come together to be the Corytopia I'd hoped to have, and that people on this forum helped me plan out.
I also discovered my Betta has a green thumb, and when I buy plants, I first put them in with the Betta for several weeks to get a lush growth of roots. Betta poop water is just awesome fertilizer. The Betta now has a small filter in his tank, but even so, with plants surrounding him, it's amazing how I was able to cut down his water changes in such a small tank & still see him thrive. Once the plants are thriving, I transfer them to the 40 gallon tank, where there really is no fertilizer--just plain gravel. I pile marbles around the base to discourage Clementine from totally uprooting them. The few that don't survive Clementine's antics get thrown back in with the betta to recuperate. I'd originally intended to follow Apistomaster's suggestion of sort of potting my plants within the tank. But I never could make up my mind how committed I felt to having plants in the tank. I started out just by throwing them in, barely even bother to root them. It was my Betta who demonstrated what plants can do for a tank. However, I can not envision myself getting high-tech with them or using fertilizers. Not with so much wonderful poop and a helpful Betta at my disposal! The betta poop dissolves so fast I really can not vac it out.
As for the main tank, Clementine is the super pooper of the group, but I find I have my filters set up just right that I don't need to poop vac in there very often, either. I've checked the filters a few times and the poop is always in there, not on the gravel. 2 Eheim cannisters going full blast really do an awesome job!
I also no longer do water changes to the 40 gallon tank anywhere near on the scale I had done before. I still do a small weekly changeout, but really with the Chemi-Pure & all the plants shoved into that tank, it's not necessary, just a small precaution.
I have absolutley no plans to add any more cories to this tank, but I am waiting to see how long the Pandas live in my current setup, and it will be a good test of whether or not I've hit on a setup that will prove to be stable enough for these little delicate cories. Trust me, I've made a lot of mental notes for the preparation of a future tank.
Tanks: SeaClear Acrylic 40 US gallons, Eheim Ecco 2236, Eheim Classic 2215, Fine gravel & EcoComplete: 3 Albino Aeneus, 4 Green Aeneus (NOT Brochis) 6 Peppers, 3 Sterba, 1 Elegans, 10 Danios, 3 panda cories, 1 cichlid.
5 gal betta tank: 1 male betta
50 gallon SeaClear Eheim 2213, Eheim 2215, fine gravel: 3 baby goldfish (2 Moors, 1 Oranda in QT)