Help. Algae on sand AFTER tear down

[Cbray305]

Hey all, about a month ago, i did a strip and clean with 90%water change, and rinsed the sand, which i thought was thoroughly clean, however did cloud a bit when added back to tank. After a couple of weeks the sand started the green, and now i have these batches. The reason for my tear down was the algea on the sand. My nitrates sky rocketed this past week past 40. Just did a 30% water change. Any suggestions, added clean up crew?
55 gallon 1.5 years old.
1.25 salinity
0 amm.
0 nitrite
40+ nitrate (api kit)
Need to do a phosphate check again after water change
Calc. 440
Alk. 9
Light-2 fluval sea marine 3.0
100% blues and purples 3%whites

 

[Billldg]

I would definitely try to get your N03 and P04 down. I would also add a CuC with Trochus snails.

 

[Cbray305]

Thank you. Not sure why they sky rocketed within the week.. ill get some phosband and try to adjust my skimmer also

 

[ScottB]

Some GFO is likely warranted, however before starting that I suggest you geta Hanna ULR Phosphate checker.

That is the only way to know where you are starting from, and where you are at along the way. Bottoming PO4 has consequences far worse than algae. Trust me.

 

[Cbray305]

I have a hanna, just waiting for things to settle adter this water change to test again. Thank you