Hehe. Thanks. I have had the pH difference pretty much since shortly after I set up this tank so I think my old test is reading close enough. And I have subjected my goldfish to sort of large water changes in the past without them showing any stress (but the same pH discrepancy is also present in my tropical tank and those guys--well, you can probably guess how often they get fresh water, but when they do it's in small packages. They have the same sand. I blame sand for the low pH.)
I do have an ammonia test but the fish are way too happy right now to have any of that
I'll order some new bulbs and ya know, maybe that will help. My plants haven't really recovered since they were dug up, moved, and transplanted 2 years ago. Perhaps I just need a little plant competition!
I don't suppose heating the tank would suppress the stuff would it? Wow have I really gotten that lazy? There's no reason to clean the filter for an algae problem is there? It's really such a minor algae problem...