Help my tank has high nitrate

[Beetlekush]

I am surprised a 40g got so high. It is just small enough that a big water change would drop it. It isn't like it is overstocked.

Is the sand or something filthy?

I done did a 100% water change and withing a week it was back up to 160 ppm I also got the sand from amazon is the fiji pink 40 lbs I try to keep it clean as much as I can especially when doin water changes

 

[Tamberav]

I done did a 100% water change and withing a week it was back up to 160 ppm I also got the sand from amazon is the fiji pink 40 lbs I try to keep it clean as much as I can especially when doin water changes

did it ever test lower? Test kit problem maybe? What test kit do you use? maybe I missed it.

What do you feed the fish and corals?

 

[Beetlekush]

did it ever test lower? Test kit problem maybe? What test kit do you use? maybe I missed it.

What do you feed the fish and corals?

Test kit api and yes it did for a while after the cycling also had it tested at local pet shop I only feed them pellets and some baby brine shrimp I dont feed the corals since the only ones left is 2 mushroom and green star polyps I want to get more corals but I'm afraid too

 

[BroccoliFarmer]

If you did a 100% water change and it is back up to pre water change level, you have a bigger issue than bringing them down. You have a nitrate factory that you have not found the source of. Over feeding, silicates, something is causing your nitrates to spike. Treat the nitrates but look for the source too.
Nopox and macro algae are great answers.

 

[Beetlekush]

If you did a 100% water change and it is back up to pre water change level, you have a bigger issue than bringing them down. You have a nitrate factory that you have not found the source of. Over feeding, silicates, something is causing your nitrates to spike. Treat the nitrates but look for the source too.
Nopox and macro algae are great answers.

Thank you and I will star the NoPox soon and keep my eye on it and if that dont help I was thinking of the algae scrubber