Veiltail looks a bit hurt - advice?

So I noticed that one of my veiltails looked a bit lethargic. Because
of the size of their tank (50G) and the fact that there are only two
of them, I've only been doing water changes every 2 weeks. Apparently
I slipped a little, and the nitrate levels went up to between 20 and
40ppm, which isn't ideal, but hardly heinous (when I 'rescued' these
fish, the nitrates were over 300, and there were 4 of them in a 15G
tank). I've started water changes every 2 days until it's back under
control.

However, I noticed that my big veiltail seems to be hurt on his
underside, just under his gills. I suspect that it might be from him
resting on the bottom, just around some gravel. (The bottom of the
tank where they normally stay is bare, save for some stray gravel that
they've picked out of pots.) The wound looks white in the centre, and
a bit puffy and raw, and red around the sides. It doesn't look like an
infection or parasite, but I could be wrong. The other veiltail, who's
smaller and usually more sensitive to changing water conditions is
happy, fins up, and fairly active. He has no such lesions or abrasions
on his body.

Nitrates/Ammonia are 0.
The hardness is fairly high, but that's typical for around here.
The alkalinity seems a little low - around 80. It's usually around
120.
The pH is around 7.2 - 7.8. I think it may have dipped below 7.2 for
one test, but that was right before a 50% water change. It looked like
it was back up at 7.2 right afterward.

The tank also seems to have a bad problem with algae, which leads me
to think that the nitrate levels would be a little higher if they
weren't taking that and the phosphates out of the water. The live
plants that I planted are also covered in algae, and it's a bit of a
fight to keep them alive. After this little storm has passed, I think
I'll try to keep the water changes at once a week, despite the volume
of water to goldfish ratio.

I would be looking a bunch of this up on the puregold site, but I
can't seem to get through.

Thanks,

JS

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Jan Sacharuk Member in Good Standing of The Discordian Solidarity
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