what causes nitrates to drop?

[epjan7]

What would cause nitrates to drop?
My water parameters were 6.8pH, 20-40ppm nitrates, 1kh and 2gh. I noticed ph swings and with baking soda and seachem equilibrium, I got my levels steady where they should be 5kH and 6gh with 8 ph. Water needs to be somewhat hard for mollies.

I added a new light last week (2 24w t5ho) on my 20g tall. Compared to my old 15w bulb. And jeeze my tank has been taken over by brown diatoms!

Havent changed water in a week and somehow nitrates dropped? I also add flourish and flourish excel.
Could this just be that my amazon swords are finally thriving?
Its a plabted tank with two amazon swords and im adding brazilian pennywort, java fern, ludwigia, and im attempting dwarf baby tears today.

 

[mrvincent]

What nitrate test are you using ? You must shake bottle #2 like if you life depends of it. Bang it on a table, shake it like **** !

If it's a 3 bottles kit, then that's the bottle #3 you need to shake like hell.

 

[epjan7]

Api I do shake it really good

 

[mrvincent]

I have API nitrates test 2, you must bang it, shake it stronger you can, else you will have a 0ppm reading, like I always had before...

I seriously don't think amazon swords drain nitrates like that with the lights you have and without CO2 injection... Did you bought the 2x

Do your plants look healty ?

Did you have very much diatoms ?

Is that light you bought ? http://www.amazon.fr/Glo-Galerie-Suspendue-T5-2x24/dp/B00E4B5GQE

I have the same on my 29g wide but 2x39W, my nitrates dropped at 0 once when I got green water...

 

[Fishfur]

Fwiw, the diatoms will probably go away on their own. They'll use up the silicates that are in the tank and dwindle away. Or you can get a snail, most snails love the stuff. Nerites especially love diatoms, eat it like candy.