I asked this question before, and you can stack energy particles indefinitly without any limit (energy particles i think are prot, neut, phot, elec, grvt), with the exception of thdr, you can stack thdr indefinitly without any limit too.
Without E-hole, the limit is 5 particles in one pixel. The only particles that don't count towards that are EMBR, energy particles, FIGH, PLSM, and THDR. If you go beyond 5 particles in a pixel without E-hole, there is always a chance of things turning into BHOL.
With E-hole, the stack limit goes up to 1500.
Or you can use every 5 layers you set a conv up with ctype your output element from the bhol (bhol powers it) and set the tmp of the conv to bhol