So2 testing ain’t cheap. And I know lots of people avoid those titrets for red wine. It says so right on the packaging “recommended for white wines”. But they CAN be used for red wine. It’s just not as easy to see color change. They give accurate enough readings for what we need. And if not investing in a more expensive method-there’s no need to choose to not test at all instead of using titrets. This was checking the level after dosing at crush a couple months ago. A box of 10 tests is about $20. I also bought the “titrator” which makes it even easier to use. Each test is in a prefilled glass titret and a rubber tip for suction of sample. There is a white line and black line on the tip. The hose gets inserted into the tip and pushed down until it reaches the white line. The black mark is scored and the point where it needs to be broken. Insert the titret up through the titrator, hose end first and push all the in. When you bring that lever down it will crack the tip on that black line Once cracked and the solution drops into the glass it turns black. This is the starting color. Finishing color is when the sample turns back to original color of the wine. Now it’s just a matter of pulling enough sample until finished. Just need to start going slow when it gets close. No different than a TA test by color change. There’s a little bead within the plastic hose tip you press on to pull up some wine Now At the point when you start pulling in very small increments and checking color. This one is at 36ppm and color still darker. 34ppm. Sample Still darker than the wine. 31ppm still noticeable darker 26ppm looks pretty close. Maybe a hair darker And 23ppm looks right on the money. Not exact- but it’s definitely close enough. Better to have an idea than to not know at all. Figured this might be helpful to anyone who has dismissed using these for red wine without actually trying.