BRS Dual Reactor seems to be absorbing Calcium and dropping CAL to very low levels/media gets rock hard and white film on canisters/media

[PhoenixOne]

Hi all!. New member. Was recommended this site by Bulk Reef Supply aquarist help center.
I have a BRS dual reactor with HO GFO and Rox Carbon. I never had a problem with the reactor and change media roughly every 2-4 months.
While doing regular bi weekly tests, I noticed my calcium was dropping after a water change last June to 297. Alk was 12.7, PH 8.2.
I slightly raised calcium on my doser and a month later Cal 338, ALK 11.1, PH 8.08. I then started struggling getting CAL up to 400s. I raised the CAL doser slightly and finally in Nov my CAL was 442, ALK 9.1, PH 8.34. I noticed my GFO was no longer tumbling and started to see white film buildup inside both GFO and Rox Carbon canister. When I opened it up, both media were rock hard and both had white film on media and as I rinsed them, the water was milky white and reactor sponges where hard. I cleaned everything out and returned the reactor under the cabinet. A few days later, it happened again and has continued to happen every few days after loosening and rinsing the media. From Nov to Feb, CAL was 400's avg and ALK was between 7-9, PH in the 8's. Then in Feb, CAL started dropping and continued to drop for entire month of FEB. PH still in 8s, ALK from 9-11 dkh. Brought a Colormeter MAG tester (2nd gen) and MAG 1450-1500.
It looks like the BRS media is absorbing the calcium which it never has done this all the years ive had it. I moved the reactor pump to middle chamber of sump, still happened. My doser tubes are located in the sump directly over my return pump and my Magus doser staggers dosing times. I brought a Syncra Silent 2.0 Pump (568 GPH reactor pump to replace the 1200 that came with it in hopes that maybe it needed a little more power to keep the GFO tumbling and not get hard but it happened again.

I am at a lost. I've had the reactor for years and never experienced this until now. I use BRS HC GFO and BRS Pharma Cal and ALK and BRS Pharma MAG. I never use more than recommended media. I started following BRS Randy and Ryan's "less water changes and dosing method a few years back with great success.
I hope there is a solution to this odd phenomenon.

Thank you so very much.

 

[Randy Holmes-Farley]

Iron Oxide Hydroxide (GFO) Phosphate Binders by Randy Holmes-Farley - Reefkeeping.com

What else might iron oxide hydroxide do? Precipitation of CaCO3

Many aquarists using GFO have reported unusually extensive precipitation of carbonates on the solid GFO, and elsewhere in the system. Such precipitation can, for example, be a contributing factor in the caking of such materials, and can coat other surfaces in the aquarium. This precipitation can also contribute to a drop in alkalinity and possibly pH as it removes carbonate from the water column. The effect of calcium will be similar, but smaller on a percentage basis, with a drop of only 20 ppm calcium for every 1 meq/L (2.8 dkH) drop in alkalinity. Increased calcification by corals and coralline algae (possibly spurred by reduced phosphate) can also cause similar drops in calcium, alkalinity, and pH.

Dissolution of these precipitates with acid, accompanied by bubbling, indicates that these deposits are carbonates, and are most likely calcium carbonate since it is supersaturated in most reef aquaria (and in the ocean). Several factors may contribute to this precipitation. Many of these are rather straightforward. It is known, for example, that phosphate inhibits the precipitation of calcium carbonate. Much like the role that magnesium plays in seawater, phosphate binds to the growing calcium carbonate crystals, poisoning their surface against further precipitation of calcium carbonate. Many organic materials are also known to inhibit this precipitation. Near the surface of the GFO, and downstream from it, the organics and phosphate are expected to be lower in concentration than upstream from it. The reduction in concentration of these inhibitors may well permit increased abiotic precipitation of calcium carbonate on such surfaces.

Two more esoteric events may, however, be equally important. The first is that the local pH near the GFO surfaces may be higher than in the bulk solution. This effect arises as phosphate and other inorganic and organic ions displace hydroxide from the surface. Figure 2, for example, shows phosphate displacing two hydroxide ions. The net swap of HPO4-- for 2 OH- will raise the local pH. The supersaturation of calcium carbonate increases as the pH rises, driving the precipitation of calcium carbonate.

Another possible role may be played by the iron itself. GFO is not completely insoluble. The solubility of iron hydroxide in natural seawater is small, but still significant (0.02 - 2 ppb), although it is largely controlled by the availability of organic ligands.11-13 One interesting possibility lies in the way that soluble iron actually impacts the precipitation of calcium carbonate.

At high concentrations, iron inhibits the precipitation of calcium carbonate. While different researchers find different threshold concentrations for this inhibition (>25 ppm in one case,14>7ppm in another case15), it is a well established and studied phenomenon. The mechanism is believed to be the same as for magnesium, phosphate, and organics, which all poison the growing calcium carbonate surface.

At much lower concentrations, however, iron actually increases the precipitation of calcium carbonate by acting as a site for nucleation of new crystals. In one case this happened at 100 ppb dissolved iron, increasing the rate of scaling (the precipitation of calcium carbonate on surfaces) by about 60%.14 In another case, the induction time for precipitation (that is, the time it takes for precipitation to begin once the water becomes supersaturated) was reduced by 40% at 1.4 ppm iron and the overall precipitation rate was increased by 32% at 560 ppb (lower iron levels were not tested).15 These studies were carried out in freshwater, and I have not seen similar studies in seawater.

Is the natural dissolution of GFO important in the nucleation of calcium carbonate precipitation? I am not sure. But it is clearly one possible explanation that fits the observations of aquarists as well as known phenomena involving iron.

 

[PhoenixOne]

Thank you for your quick response. I've read and re-read your response several times and unfortunately I am having difficulty understanding your response due to it being very detailed in the aspect of chemistry which I'm not very well versed.
I apologize, but is there a way you can simplify your reply for someone as myself that is not savvy with chemistry and the terms you used?
Again, I apologize and embarrassed that I am unable to understand it all.
Thank you so very much.

 

[Randy Holmes-Farley]

Thank you for your quick response. I've read and re-read your response several times and unfortunately I am having difficulty understanding your response due to it being very detailed in the aspect of chemistry which I'm not very well versed.
I apologize, but is there a way you can simplify your reply for someone as myself that is not savvy with chemistry and the terms you used?
Again, I apologize and embarrassed that I am unable to understand it all.
Thank you so very much.

Sure.

GFO accelerates the precipitation of calcium carbonate in various ways, so reefers often see what you see.

Reducing alk and pH will reduce the effect. High alk with GFO might not be optimal for this reason.

 

[PhoenixOne]

Ah. Very good! Thank you so very much. I will lower my ALK and my PH and see if it will go back to normal.
Again, thank you So very much for your help!

 

[Randy Holmes-Farley]

Let us know if the issue changes.

 

[PhoenixOne]

Will do. Again, Thank you SO much!

 

[PhoenixOne]

Ok. So I lowered ALK to 9. PH to 8.0 and both GFO and Carbon (ROX) still ended up getting rock hard. I put new Carbon and GFO on Feb 25 and by MAR 7, GFO/Carbon ended up getting solid. I shook the reactor during the "watch time" and raised the flow to keep it moving and lowered it so not for it to get powdered from too much agitation. Carbon media ended up becoming black and white. I've previously rinsed it in a bucket when it got like that and the water was milky white. When I started with new media, my calcium was 354. It dropped down to 297 which tells me the Carbon is most likely absorbing my Calcium and dropping the levels.
So basically, same thing is happening. GFO/Carbon gets rock hard with Carbon becoming black/white.
Darn it all.

 

[Randy Holmes-Farley]

Ok. So I lowered ALK to 9. PH to 8.0 and both GFO and Carbon (ROX) still ended up getting rock hard. I put new Carbon and GFO on Feb 25 and by MAR 7, GFO/Carbon ended up getting solid. I shook the reactor during the "watch time" and raised the flow to keep it moving and lowered it so not for it to get powdered from too much agitation. Carbon media ended up becoming black and white. I've previously rinsed it in a bucket when it got like that and the water was milky white. When I started with new media, my calcium was 354. It dropped down to 297 which tells me the Carbon is most likely absorbing my Calcium and dropping the levels.
So basically, same thing is happening. GFO/Carbon gets rock hard with Carbon becoming black/white.
Darn it all.

Does the dosed alk get to the intake point for this reactor before it is well mixed into the while tank?

 

[PhoenixOne]

Does the dosed alk get to the intake point for this reactor before it is well mixed into the while tank?

The reactor pump is located in the middle chamber of the sump. The dosed alk is in the 3rd chamber right above the return pump so it gets sucked in and into the display tank. So the reactor pump is not intaking any ALK or Cal.

 

[Randy Holmes-Farley]

The reactor pump is located in the middle chamber of the sump. The dosed alk is in the 3rd chamber right above the return pump so it gets sucked in and into the display tank. So the reactor pump is not intaking any ALK or Cal.

I cannot see why you are having a more extreme precipitation issue than is normal (some is normal).

Like other precipitation issues, breaking the cycle of exposed calcium carbonate is important, as is keeping alk and pH down. New carbon and GFO should have broken the cycle on that material, unless the alk or pH is higher than you think.

 

[PhoenixOne]

I am using Hanna checker for CA and PH (i calibrate PH every week). Ok. I will buy what everyone seems to deem accurate, Salifert CA, ALK and PH and see if Hanna is way off. If so, then the problem is found (hopefully).

I will keep you updated!
Thank you so so very much for the amazing help!

 

[PhoenixOne]

Ok,
I purchased Salifert Calcium, Mag, Alk and PH.
Most recent tests:
Hanna Ca - 465. Salifert - 445
Hanna Mg - 1545. Salifert - 1305
Hanna Alk - 8.7 Salifert - 8.7
Hanna Ph - 7.81 Salifert - 8.0

Looks like Hanna's new Mg checker accuracy is in question even though the "2.0" checker was supposed to solve the excessive high test results that the "1.0" checker was giving everyone who brought it when it first came out.
Although the 240pm difference isn't that excessive, it is something to note when using it.

I am glad to report that GFO no longer becoming solid. The ROX carbon is still getting partially white but checked the media 3 times since last post and also no longer becoming solid. Looks like dropping Alk and Ph may have solved my problem. I will continue to monitor but looks like my problem is solved.

Thank you SO much for your help Randy. Greatly appreciate the time you took to help.