Interesting...calcium reactors and phosphate.

[Anonymous]

Just changed the media in one of our reactors and we are testing phosphate levels in the effluent every hour. The old media (same brand, but had just been in the reactor) discharged a phosphate level of 0.0 ppm (mg/L), after 6 hours the phosphate level of the effluent from the new media is at 0.35 ppm (mg/L). And climbing. I'm curious what it's going to be like tommorrow morning. Apparently other people who've done this report it spikes for the first few days and then drops to zero.

Is this news to you guys or am I catching a late train here?

 

[Anonymous]

The dropping to zero part is news to me.
I thought all CaRx media released some amount of phosphate as it dissolved.

 

[ChrisRD]

Interesting. Like Marcus, I've always just assumed that some phosphate was present in the effluent at all times...

Keep us posted on the results Matt.

 

[Anonymous]

Yeah, duh. I guess I shouldn't say zero, as technically there is always some coming out of the reactor. What surprises me is the big spike right at the beginning, and I'm wondering exactly what causes it and if it can be avoided. The phosphate level of the effluent is 0.25 ppm this morning, pH 6.7.

 

[Anonymous]

Do you rinse the media before using it?
I'm wondering if there was something on the media that causes an initial spike in the readings that dissipates as it gets washed away.

 

[bleedingthought]

Matt, are you testing different brands?

 

[Anonymous]

Do you rinse the media before using it?
I'm wondering if there was something on the media that causes an initial spike in the readings that dissipates as it gets washed away.

Yes, very thoroughly, with dechloraminated fresh and saltwater. I think the idea is that there's a higher concentration of phosphate on the outside layer of the media. It doesn't seem like it comes off from rinsing.

 

[Anonymous]

Matt, are you testing different brands?

Nope, although it'd be great if other people could do some tests with other media at home.

 

[Anonymous]

Huh. Looks like the phosphate spiked about 6 hours after we replaced the media at a concentration of around 0.35 ppm. It's now at 0.19 ppm about 30 hours after the initial replacement.

 

[Anonymous]

That is interesting. What type of media are you using?
To be honest, I never test for phosphate. I just assume its there and run GFO 24/7. So for all I know, my media does, and has done, the same thing all along.

 

[Anonymous]

That is interesting. What type of media are you using?
To be honest, I never test for phosphate. I just assume its there and run GFO 24/7. So for all I know, my media does, and has done, the same thing all along.

I'll check the brand today, but from what I understand this happens with any natural media.

We're thinking about either a) diverting the effluent flow down the drain until the phosphate drops to an acceptable level (water change) or b) giving the media some kind of acid bath for a short period before using it.

 

[Anonymous]

Next time acid wash the outside of the media briefly with a weak solution of pool pH reducer (HCl) added to di water. Rinse the media well in DI. If the Pi spike is due to Pi adsorbed to the surface of the media, basic seawater and tapwater ain't going to rinse it off.

Info on the media would be good, too. Composition, size, source, etc.

You're supposed to be the professional!!!

 

[Anonymous]

Yah, what he said I got some pretty high % HCl Matt if you need any