Nitrate levels high

[Chris king]

Hi again everyone just thought I’d post an update on this, the nitrate filter arrived yesterday and I immediately done a 50% water change including sand clean ect . This brought the nitrate level way down to 20-25ppm and I couldn’t be happier with the filter itself. il be carrying out water changes weekly to lower the level gradually and hopefully it will stay down now! BUT it seems one problem is semi solved another has developed ... don’t know if it’s actually anything to panic about but my sand seems to be turning brown in patches ? I’ve done some research and something called diatoms came up don’t know if this is the cause though? Any suggestions ? Il try and post a photo of it
Cheers in advance

 

[Chris king]

 

[Chris king]

The picture isn’t that good but the slightly darker areas are worse in person I’ve already cleaned it once and it’s returned in 1 day

 

[FishGuest5123]

It could be brown algae which normally plagues new tanks. It is harmless, just ugly. No harm yo fish. If it is brown algae, you can simply vacuum daily or every couple of days. It may grow quickly on your glass too. Just scrape it off and do your water changes. It will eventually resolve itself it that is the issue. High nitrates can also contribute to it so your filter should help. Good luck.