Crazy high phosphates with 0 nitrates

Solasis · Jul 30, 2023

Hello! I have a 300 gallon reef tank, around 2 months old. Honestly all of my corals have been looking good, my birds nest is growing and all my euphyllia seems healthy. No new growth on the LPS but doesn't look unhealthy either. Well I had some cyano show up so I invested in the phosphate low range checker by hanna. Ran it last night and it showed 2.25 ppm! I was blown away. I checked my nitrates using the salifert test and they seem to be at or close to 0.

The rock I am using in this tank is probably 15-20+ years old, it's mostly dead coral skeletons I got when I purchased my tank second hand. Would these be causing the massive phosphate leaching? I just got my refugium back up and running to hopefully take a dent out of this..

christianscorals · Jul 30, 2023

yes, I believe the skeletons may be the culprit.. especially after a transfer. run some GFO and dose nitrates to keep your corals happy!

Solasis · Jul 30, 2023

christianscorals said:
yes, I believe the skeletons may be the culprit.. especially after a transfer. run some GFO and dose nitrates to keep your corals happy!

Thank you, I'll order that in. Is there any worries with high phosphates harming fish in the mean time?

christianscorals · Jul 30, 2023

the fish should be ok. maybe @TheScientificReefer could chime in. he just went through a similar situation in his tank and used GFO to bring phosphates down overtime as well.

Solasis · Jul 30, 2023

christianscorals said:
the fish should be ok. maybe @TheScientificReefer could chime in. he just went through a similar situation in his tank and used GFO to bring phosphates down overtime as well.

Thanks. I'm just so confused because I feel like all of my corals should be dead.. atleast my SPS. But I tested 3 times with my hanna checker 3 times and got a range of 2.0-2.25 ppm so should be accurate

TheScientificReefer · Jul 30, 2023

Solasis said:
Thanks. I'm just so confused because I feel like all of my corals should be dead.. atleast my SPS. But I tested 3 times with my hanna checker 3 times and got a range of 2.0-2.25 ppm so should be accurate

Its like @christianscorals is saying, GFOs are the way to go if you want to steadily bring them down, use as many bags as appriopriate given the instructions. And they should drop at a safe rate given the culprit is taken out of the picture.

In my case it was overfeeding. I went from .79 to .25 currently in about a month and a half (I continue to feed alot just not as much as before)