To add or not to add phosphate and nitrate

Skibi · Oct 14, 2018

So I stopped nopox on Friday and didn’t do my water change this weekend I’m at .1 phosphate and no nitrates still lol.

Dan_P · Oct 15, 2018

Skibi said:
So I stopped nopox on Friday and didn’t do my water change this weekend I’m at .1 phosphate and no nitrates still lol.

For my heavily fed fish only tank with a lot of macro algae, PO4 doesn’t vary much, but I have seen daily “yo yo” nitrate levels after feeding. It would increase overnight and come down during the photoperiod, a swing of 1 or 2 ppm. Reducing the feeding rate resulted in undetectable nitrate in a couple of days. Typically, the nitrate level is undetectable.

I mention this as an example of how fast nitrates can come and go in an established system. So, if you are not seeing nitrate in a week or two, your system’s denitrification bio filter might just be working very well.

Bigfudge · Oct 16, 2018

I'm a little late to this party, but I was right there with you. My tank was at 0 phos and 0 nitrate and things weren't looking so hot. Being a newer tank, and being a newb to the hobby, I had been running GFO 24/7 since the start to keep Po4 down with the new dry rock. It worked too well haha.

After I had a velvet out break, I removed all my fish and had no way to get nutrients back in and had considered dosing No3 and P04 but after some reading, I wasn't comfortable with doing it myself.

Instead I removed GFO, Fed food normally and just kept monitoring. Eventually I started to read a little bit of Po4, then a few weeks later, No3. Took some time but it worked itself out. I still haven't added any GFO back to the mix. Everything looks healthy and I'm around 1ppm No3 and P04 is .04ppm now (two months later). I'd rather be around .02-0.03ppm P04 but I'm ok with it as long as things look good.

I was really scared I was going to get Dino's.

Skibi · Oct 16, 2018

Ya it’s crazy I haven’t ran gfo but I have a fuge. I’ve still been doing my normal feeding everyday and stopped the water change this week also completely cut out nopox. A day or 2 ago I was at .1 phosphate 0 nitrate. Tested last night .003 phosphate and 0 nitrate can’t believe it’s reduced that much in 2 days or so

Dan_P · Jan 12, 2019

Randy Holmes-Farley said:
It's complicated, but it is a clear empirical result.

Most likely, at higher nutrients, something else outcompets the dinos for a critical other element, such as iron, but at very low nutrients, that competition is reduced or stopped when the other organisms stops growing.

A possibly more straightforward link between low phosphate concentration and algae blooms is a low phosphate level triggers a change in feeding habit to mixotrophic feeding on bacteria which are good at accumulating phosphate. This phosphate rich diet would then trigger the bloom.

For example

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1993.38.2.0273

Flippers4pups · Jan 12, 2019

Dan_P said:
A possibly more straightforward link between low phosphate concentration and algae blooms is a low phosphate level triggers a change in feeding habit to mixotrophic feeding on bacteria which are good at accumulating phosphate. This phosphate rich diet would then trigger the bloom.

For example

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1993.38.2.0273

Thanks for the post. Will definitely read it!

Skibi · Jul 11, 2019

Old thread but phosphate and nitrates bottomed put on me again while I was on vacation on the 4th. Came back to dinos on the sand bed. I hope this battle isn't as bad as everyone says it is. I really regret starting a refugium from.day one tank has always been to clean my next tank will wait till it needs it.

ihavecrabs · Jul 11, 2019

Skibi said:
Old thread but phosphate and nitrates bottomed put on me again while I was on vacation on the 4th. Came back to dinos on the sand bed. I hope this battle isn't as bad as everyone says it is. I really regret starting a refugium from.day one tank has always been to clean my next tank will wait till it needs it.

Start dosing! Best thing I did was add a UV and it cleared mine up in 36 hours. All depends on the type though.

Skibi · Jul 11, 2019

Ya last 3 days been dosing nitrate and phosphate hoping for the best also adding bacteria in and have pods on the way with phytoplankton.

ihavecrabs · Jul 11, 2019

Skibi said:
Ya last 3 days been dosing nitrate and phosphate hoping for the best also adding bacteria in and have pods on the way with phytoplankton.

I did the same thing along with manual removal and while it made a dent it was temporary. UV is what did it for me. Best $90 I’ve spent on my tank lol