All the fish seem to be fine this morning. No deaths and none seem worse for wear. Last night though, even dumping in some Tetra flakes had them motionless.
To answer some questions...the filter is the standard filter that comes with the Marineland Eclipse 3 gallon tank. It is a above the tank/under the hood style. It has a power head that pumps water across the top of a filter floss cartridge that then drips through to the carbon/charcoal below and then that falls over a bio-wheel, and back into the tank. I have modded the cartidge to make it reusable, in that I peeled up the floss from the frame and replaced the stock carbon with a known brand and also added some zeolite in a roughly 50/50 mix. Where the standard cartidge is about 10 percent filled with media, it is now 100% filled with my mixture. This was last changed at the beginning of the month. i also have a Tom's internal filter with a block of foam sitting below a media chamber, which is also filled with my own carbon. This was changed a few days before the introduction to Purigen.
The Purigen changed color where it was touching the filter pad. It went from it's stock sandy color to red and brown in a few places. This was within one hour of application. yes, it was sitting on a dirty filter pad, but the pad had been rinsed and brushed maybe a week and ahalf earlier (in siphoned tank water). Pad was relatively clean at the time with good flow throughout.
Purigen was brand new, bought online, but from a vendor new to myself (Phenter Sales $4.95 for 100ml). It appears to be new, was in a heat sealed bag inside the box, with an instruction sheet). Having never used the stuff before, I thought it strange that even after wetting it, it still appeared to be dry, but I'm assuming that it does not absorb liquid, but instead adsorbs organics. I'm assuming that it's legit and brand new. I've not had to recharge it as it is new, and it did not have any odor. I've also not used amine based dechlor in well over a year.
Water parameters...gonna get flamed here!!! Bioload is immense!!! 3 gallon tank. 12 full grown fancy guppies 9a few more females than males), about the same amount of babies 1/4" to 3/4" length. Every day I seem to have more new borns as they typically give birth to a few per day, and the birthing process lasts for a few days for each female. Many, many have remarked that my guppies are the largest guppies they've ever seen. I've got newborns pretty much every day! I'm at the LFS giving away fish every week
There's also about a dozen or so adult Malaysian Trumpet Snails, but another dozen or two or three babies. Also, 4 Nerite Snails (egg laying everywhere), and a small red-clawed crab.
As my PH levels are always falling weekily into the below 7 range from my tap water of 8.2- 8.4, I do a once or twice weekly water change of about 33% (1 gallon changed out of 3, by way of a gravel vac siphon).
So, my fish are quite used to PH swings. No ick, no disease, no deaths, just non-stop breeding.
Water is very soft. About 10ppm from the tap, but typically verrrry high in the tank (400->999ppm) depending on when I test. Again, all inhabitants seem to be used to this and appear to getting on without issue.
No copper, no nothing, other than Prime, Flourish (1 drop every day to two days), the occasional bacterial supplement if I feel the need to do a big cleaning, and some API salt (1/2 tsp/gallon) somewhat often when doing a water change (not during top-ups). Even the few floating plants are growing like crazy.
i guess it is possible that the bag of Purigen might have caused a dam atop the filter pad, preventing water from flowing across the full surface of said pad, but the bio-wheel was still spinning at its normal rate, and the purigen was discolored almost totally along it's bottom side where it had been resting upon the filter pad. I'm going to assume that if the pad was having a blockage and bacteria were dieing, then I would have seen rapid gilling and other symptoms of oxygen starvation/toxicity. The fish' gills were barely moving, and my guppies are somewhat translucent, like ghost shrimp, but not entirely clear (translucent bodies, bright orange tails-females) I can see their gills and they were not red. The fish appeared to be sleeping in the light, or doped up. Maybe the Purigen got them high
Edit: forgot to add, I've got a small piece if cuttlebone on top of the filter pad that was in contact with a small part of the Purigen bag. I also throw about 1/4 piece of a Tums (the stuff used for heartburn) into the tank a couple times a month to add some harness to the water, and help with snail and crab shell erosion.