In fact just ordered some bottle top filters for next experiment.
Zapcaps? There good but take more like 45mins to filter 500ml over 15mins fastcaps.
Plus fast caps are ment to filter upto 4litre I think, zap caps are just about done after 1-2fills 500-1000ml on the 500ml zap cap. So saving $10 per filter if you go with zap caps but depends how much you filter in 1 go if its werth it.
You could have 1000ml to filter then the fast cap would be cheaper as u may need 2 zap caps to filter that
Fast cap being $25 and zap cap being $15.