Thanks for the feedback. I don't think the black tank empty because it didn't run as long as the first 2 times I dumped it. The first 2 times were about a minute; today maybe 30 seconds or less. Also, the bathroom has developed a noticeable stink in the last 36 hours or so. Also, I just got back from the store and I checked the gauge. It said 2/3. I went out and opened it and it flowed for maybe 10 seconds. Then I closed the valve and re-opened it and a few more seconds came out. So I opened and shut the valve a few more times and got a few more seconds to run out. It's back down to about 1/3 reading, so the reading is changing.
I bought 3 products at the store for RV black tanks. One is RV Digest-It which I think is like Liquid Plumbr for RVs. I also bout the TST Max packets to put in the toilet and a product from Walex called Commando. I'm going to read up on those and see if they help clean it out.
As for leaving the gray tank open, they both exit the same dump opening, but they have different handles. I'm sure the black handle is the black tank from watching the clear end on my dump hose. Other campers have told me when they empty into a coming hose (mine do) it's best to dump the black tank first and then dump the gray tank to flush out the hose, and maybe it helped the common exit point because it seemed to flow more after dumping some gray water, but it still reads 1/3 full on the Black tank and empty on the gray.