The Shrimphaus gets some light brown coloured algae-like material growing on the glass which needs periodic scraping off. It won’t just rub off casually, but it comes off using a credit card blank relatively easily. It does seem to happen more in regions of higher lighting. It isn’t super unsightly, and doesn’t happen fast enough to be really bothersome, but still. I suspected diatoms (because of the brownish colour) which are pretty common in new aquaria. Reputedly diatoms are a “problem” that pretty much solve themselves over time, but seems not the case for the quite well-established Shrimphaus – these happened in the previous iteration of the Shrimphaus as well.
diatoms on glass
scraped off diatoms