Low NO3 and rising PO4 causing acro problems?

[markalot]

Does the following make sense?

When my tank was newer I had low nitrates, less than 5, and experienced a rise in PO4 which in turn caused a KH spike and killed a lot of my acros.

After a few months I started having Nitrate issues, I could not get NO3 to drop below 15 without a lot of water changes. During this time PO4 fluctuated, sometimes as high as .15 if I forgot to change the GFO. Corals stayed healthy, some kept color, others stayed brown. No losses.

During the last couple of months I used NOPOX to get my NO3 down to around 2.5. Brown corals started to show some color but then browned out. Worse, a few frags started to decline in health with 2 now showing some STN. KH has been fairly steady around 8KH, but it appears I have a pretty big PO4 issue because it tested near .1 meaning my GFO exhausted itself in less than a week.

Why is it with lower nitrates elevated PO4 can cause issues while when my Nitrates were elevated I didn't lose anything? Is this just a coincidence?

Thanks!

 

[swk]

I don't think that's really the case. My nitrates are 2.5 and po4 is as high as
.15 and everything is thriving. I would imagine it has more to do with the alk spike than anything else.

 

[markalot]

I don't think that's really the case. My nitrates are 2.5 and po4 is as high as
.15 and everything is thriving. I would imagine it has more to do with the alk spike than anything else.

Alk has not spiked for 6 months, staying between 7.8 and 8.7 at the highest after a slow drift up, then a slow drift back down. This time I feel fairly certain it has nothing to do with Alk.

I'm glad to hear your params, it does make me think it must be something else. Perhaps too rapid a change in something I didn't test for.

 

[CHSUB]

alk spikes are "highly" overrated when it comes to sps' health. sps' need food from capture and from their zoox's. provided food, and keep dissolved nutrients low and stable (no3 and po4) and you will find better success.

 

[Hockeynut120]

When my tank was newer I chased numbers such as you and had mixed results. As my tank matured, 2.5 years my nitrates hung around 15 to 20 as this happened I noticed that my phosphate also leveled off at a lower level can't say for sure what the exact number was (don't test phosphate) but it took nearly a week for my glass to have a decent amount of algae. They balanced out. If you feel that your phosphate is a little high don't run gfo change some water everything benefits.
It doesn't surprise me that you're coral looked better at this time. They had the nutrients they need.

 

[markalot]

Thanks for the replies and ideas everyone. :beer:

Here's a picture of the tank for reference. If only everything was as easy as the slimer.



Things already look better since replacing GFO, but I think I'm going to lose a blue tenuis and another small frag.

About chasing numbers ... I suppose I was when i tried to lower nitrates but I was getting tired of 6 months of brown acros and no end in site. I witnessed more colors briefly when nitrates dropped below 10 but apparenlt phosphates started to rise at the same time. I don;t test them very often so I'd like to think i wasn't chasing ...

The only thing I test often is KH, trying to avoid any rises, slow or fast, that would bring be much above 8 KH.

 

[markalot]

As far as changed to tank maintenance. I gravel vacced once so far, long overdue, and I plan to do a few more over the next couple of weeks. I've got a recirculating reactor with all-in-one bio pellets but I'm running it with very little output, trying not to shock anything. Right now it's mainly NOPOX dosing and GFO, and I am stopping the NOPOX to let the Nitrates rise again.

I'm kind of lost as far as where I want to keep nutrient levels. I know people have good luck not chasing numbers, so to speak, but I've been down that road and lost a lot of corals. Honestly if I could stabilize around 5 nitrates and PO5 .03 to .05 with healthy SPS I'd be happy. I can always replace any acros that refuse to color up.