Newbie question: Drop checker, pH, KH and CO2
Hello to all. I've kept aquariums in the past this is is the first time at planted aquarium. I've decided to go with a DIY CO2 system and see how it works before investing in a automatic system. So:
- I ordered everything I needed for the planted tank: dry ferts, water tests kit and a drop checker (from eBay).
- Before doing anything, I decided to setup the drop checker. It turned yellow which means...too much CO2?
- Ok...so I thought maybe it's inacurate. I so decided to test the CO2 using pH vs. KH on my tap water. I have both the regular pH and the High pH tests. The regular gives 6.8 and high pH returns 7.8. If both returns a value, how do I know which one I should be using? I needed 7 drops for the KH test so I guess it means a KH of 7. At pH 7.8, it's too little CO2 and at 6.8 it's off the chart.
Also, under the drop checker bubble, there is a slimy film that accumulates after a few days. What does that mean?