then you are shortening the life of your membranes.
booster pump is THE only fix to a merlin. i have been through hell and back with mine, and i keep banging on, but a clarke cbm240 pump is what is needed to get these working well.
dont belive what the merlin seller's tell you that you need to spend out on a pump - if i remember this waste back preasure fix was known about years ago - i was one of the first to get the merlin when they come out and its still going strong after 4 plus years- all ive done is change the first filter's -- same membrains from start - still comes out at 10ppm .
from my days with 200 -400 gallon ro's they worked ok till you put a booster pump on them ...
but post is about resin usage --- dont even put a di on the merlin - full stop, if you want to save money
stick it after the pump so your pump passes the 10-30 tds more slowly throught the resin .
i still wonder why people even on di fill up their van tank with the water tap on full
and wonder why they getting high tds readings -
this gam'es not rocket science - tho some like to make it so lol