Canon S630: Bulk Ink Rot

Something has gone badly wrong with the yellow bulk ink that I’m using in the Canon S630. Over the winter a precipitate formed in the bottles:

And in the ink tanks:

But now that the Basement Laboratory has warmed up, not only does the precipitate remain, but some of it is growing:

The picture doesn’t do it justice; it looks like pond scum in there. Only the yellow ink behaves like that, so it’s likely some contaminant in that batch. Because I buy ink in pint bottles, it’s a long time since that batch arrived and there’s no point in kvetching to the vendor. IIRC, I actually got this bottle from a friend who scrapped out his S630; he’d been refilling cartridges from the same source, too.

I ordered four sets of five tanks (CMYKK) from the usual eBay vendor for 20 bucks and will toss the old tanks & ink when those arrive.

There’s a set of four bulk ink bottles from a long-dead HP2000C printer on the shelf, but I suspect the ink chemistry differs by enough to ruin the Canon’s printhead… which is discontinued, so when the head dies, the printer dies, too.