I ordered a full CO2 test kit online an received confirmation. Was later sent an E-Mail saying it was back ordered; even though there was no mention on the site. I responded to cancel the order. The next day they shipped the refill kit, not the full kit. I have now purchased the full kit including titration equipment from another vendor and have wasted my money on the refill kit I will never use or need. I will not be purchasing any more items from Nature Aquariums USA.