Hey thats a cycling challenge lol! Unique setup.
The only way I can discern is the old standby: full water change to be zero ammonia. salifert or equivalent level ammonia test, add cleaners ammonia per those threads to the tank to attain 3 ppm. Test in 24 hrs and depending on how close to zero we know about your cycle progress.
Searches show these test kits having excellent consistency and there may be others too, but salifert and Hanna are excellent and $
There is no way to discern the cycle issues without getting a timeframe for 3ppm to zero, you can have 8 ppm in a tank with not enough surface area and it takes days to go away even if whats in there is cycled. You can have 8 ppm in a fully cycled tank is my point, indicating no cycle issue but an overage of ammonia issue, if you simply overload the rot and under load the active surface area. Need a few more details to really pinpoint.
Whats your active surface area in this new tank? PVC doesn't really count much
Adding a cycled sponge w surely help.
It will start to stink soon. These organics are the result of choosing the shrimp option. Cleaning ammonia is better in every way but shrimp w work too.
It takes about 3-4 weeks for basic cycling to be done when in a boosted environment and as fast as two weeks under the exacting conditions of cleaning ammonia and bottle bac or alt seed sources. Three days isn't enough for any of them and if the slime organics are that bad now, imagine the 3rd week lol
