I'm not so sure those are deposits, that may have etched the glass. I do hope I'm wrong :)
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I had feared this, I lived through very similar some years ago with a 125 gallon, I threw everything at it, including muriatic acid, and all I succeeded in doing was burning out some grass in the lawn lol!OK, I called out the big guns on calcium carbonate removal.
Bought muriatic acid at Ace. Diluted it 1:1 with water to reduce fumes, but it is still very strong (pH around -0.5, which is hundreds of times stronger than the saturated citric acid). Still fumed some, but not a huge problem for a test. A small bit of a coral skeleton dropped into it bubbled like crazy.
Wiped it carefully on a 6" spot, and after 5 minutes, followed by rinsing and wiping, no change to the cloudiness at all.
Conclusions: it definitely is not calcium carbonate.
Might be silica from diatoms, might be organics somehow (unlikely, IMO), or it might be etched glass.
My next experiment will be a buffing pad and cerium oxide glass polish on a random orbit sander.
If that fails, I'm likely going to call it done. lol
I had feared this, I lived through very similar some years ago with a 125 gallon, I threw everything at it, including muriatic acid, and all I succeeded in doing was burning out some grass in the lawn lol!
I don't know why the glass gets this way, to say it's "etched" may not be fully accurate, but but I believe the problem is "in" the glass. My only other idea would be to polish the glass.
The good news is that as you noted it looks a lot better filled :)