Just to check, have you done any of the following?
- washed your filter in untreated tap water
- used cleaning detergent near your tank
- sprayed deodorant/air fresheners or lit candles in the same room as your tank
- noticed any dead shrimp in your plants
- left uneaten food (e.g blanched vegetables) in the tank for more than a few hours
The first three are sure-fire ways to kill the good bacteria in your filter, which would lead to ammonia spikes. The fourth one is because as far as I'm aware, shrimp are very sensitive to water quality, so the ammonia could be causing them to die off, which would produce more ammonia, etc. The last one is because decomposing food produces ammonia.
I've never been very successful with shrimp, but I believe they have pretty low bio-loads. That said, a jump to 50 could have shocked the filter. You said you were thinking about adding additional filtration, but you need to make sure that cycling this filter won't add to your ammonia levels more, so you'll need to keep an eye on water quality should you add another.
The thing with nano tanks is that they are much harder to keep stable in terms of water quality, and sometimes these things just happen. Let us know if you've done any of the first three points though, as you may have triggered your filter into a new/mini-cycle.
I only washed the filter medium in the tank water i take out as i read it wouldn't harm the bacteria.
And no on the candle or cleaning medium..
Didnt find any dead shrimps infact they seemd very healthy and all over the place and reproducing like crazy infact right now aswell 2 shrimps are carrying eggs, last shrimp death was a while ago.
But the guppies are slow i dont know why and two of them did die, one i never found the body as i had exams and didnt notice it missing and when i did the shrimps had eaten it up as i looked everywhere. And 2nd one died 2 days ago but i immediately took it out.
I am guessing ammonia spike might have been the cause ?
The blanched vegetable i do keep it for 36 hours or so in a glass bowl as by then they finish it all up.. is that wrong ?? I boil it for 15 mins just a thin slice of zuchini and put it in the tank..
Regarding the filter yes i want to increase as i think such a spike in population needs more filtration.. would just connect the existing filter outlet to the new filter sump untill it completles the cycle with the help of the bacteria from existing filter. And i do keep checking the water everyweek. And water change a week or two later.