I have been using the blue foam mod and find that I can just pull out the blue foam and refill the cart with 7-8 drops
e-liquid, put the foam back in, add a couple more drops and it's good to go for hours.
I'm using a 510 from Cignot.com . Haven't tried it on the new
DSE 901 from Goo Prophets.com.
After a couple times or so of this pull and refill, or if I'm changing to a very different flavor I want to savor (I have one cart + atty +
batteries with blue and purple leds for tobacco flavors and one cart + atty +
batteries with red and green leds for all the fruity, chocolate, etc. flavors), I pull the foam and rinse it with warm water and dry it. It is good to go for a bunch more times. At some point the blue foam gets looking fuzzy, so I pull out another one. I have like a zillion pieces from the pack of 3 Marineland sleeve filters.
It is fun to experiment and see what works best for my tastes.

Vape on!