No Nitrites, No Nitrates but .25 Amonia Help?
I would guess the shrimp added more bioload than your filter was already consuming. Algae is a response to the extra ammonia. I would do daily water changes for a little while to keep ammonia near 0 and prevent further deaths until the filtration catches up. You can also look at adding zeolite to the filter which will bring ammonia down to 0 quickly as it absorbs it, but once it ‘fills up’ you may get another ammonia spike unless your filter is caught up by then. If you do this, run the zeolite as the last media in the chain, which gives your main filtration first crack at the ammonia. I used to always do this for cycling but just be aware and do daily ammonia tests because it can kick in suddenly.
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