Actually filling it right upto the hole in my case was a bad idea, when I first did that it in my Exide EL tubular battery(Not tall tubular) with micro porous vent cap, the acid water spilled over during the charge cycle.(my battery didn't come with floats). Was told by exide dealer to fill it just above the lead plates but this would cause me to frequently top it up, which PIA without float level indicators. After trail and error I fill it another .75 inch above what the dealer recommended height, again this is specific to my battery.
Yes I do have hydrometers, currently on my fourth one after previous one broke or materials inside disintegrated.
Yes distill water like the old days is not economically feasible. In one shop when I pointed out about the floating particles he said those are battery additives, I was like WTF. Those guys didn't even bother doing a basic suspended particle filtering, It looked a Snow globe. Never buy those 4 liter distill water blue, green opaque cans, one just cannot see the water inside.
Since I am not able to get consistent good distill water anymore, I am building RO based, deionizing plant. Currently my self built RO unit gives a reading of 2 to 3 TDS with input water TDS of 160 to 200. So with a deionizing filter I can get zero TDS.
