Is it possible for Alkalinity to rise in a stable system by adding Aquaforest man made rock to sump?

[A_Blind_Reefer]

Ok, I know this sounds crazy. I can hear it already, believe me. Almost didn’t even want to post this.

I have a fairly mature mixed reef tank that has been stable for a long time. Nothing more than minor swings over years. The refugium section of my sump has been unused and empty for years. On a whim I decided to add rock to the refugium section. I can barely see and ordered 22lbs of AF Base Rock (as it was half off and I had reward points to spare) not knowing it was man made or colored. My noon trident Alk test was 8.42 dkh (daily average swings between a low of 8.3 to a high of 9.1) which is absolutely normal. I added the AF Rock to my sump around 4:30pm after a quick rinse in ro (not rodi). My 6pm trident test was 10.71 dkh. I thought, no problem, the reagent could be running out or I accidentally pinched the sample line or something. I ran a Hanna test just to compare before I start diving into things. The Hanna was 10.39 dkh. I tested again, about the same. I verify my trident to a Hanna every 7-14 days just for redundancy and they’re always within .5 or so of each other. I run a saturated kalkwasser drip at my evap limit. I also run a calcium reactor that has a carbon doser and dosing pump. Neither of which are out of whack and are functioning normally. Calcium did not increase at all (I know it would be minute but the trend day over day has been spot on with this measurement). I know the answer will be testing error, or equipment issue, but honestly everything’s rock solid. Is it even remotely possible for this man made rock to add alkalinity somehow? Believe me, I’m feeling like a dummy for even bringing it up.

 

[A_Blind_Reefer]

….so it’s about two hours since I switched off the calcium reactor (co2, circulation pump and dosing pump) as well as the Kalk drip. In that two hours the Hanna test has gone up from 10.39 to 10.57. I know there is some accuracy/repeatability margin but I did test twice both times, and it’s for sure still trending upward. It’s right at the point that I’m not very comfortable being a 2 dkh swing in just a few hours. I’m not going to yo-yo this and knee jerk it back down, but I’m leaving the dosing off overnight to see where it lands. I really hope it doesn’t continue to rise. Man, I hate not being able to see. I would not have ordered man made, colored rock to fill a sump chamber. All the other brands state coralline colored either in the name, or within the first sentence of the description. This was buried in the description and they don’t even tell you what it’s made of. I made a post shortly after I ordered it as I was listening to a YouTube review talking about how it’s pink and has pieces of a pumice like substance in it. Someone replied that it’s all natural and a zeolite like not pumice. I can’t even order a freakin rock correctly! I think it’s time for the home.

 

[Miami Reef]

Rocks made from cement can increase alkalinity.

I don’t know if your source uses cement, but it’s something to look into.

 

[A_Blind_Reefer]

Rocks made from cement can increase alkalinity.

I don’t know if your source uses cement, but it’s something to look into.

Yeah, I can’t find anything other than quote all natural. It’s difficult for me to dig deep into these things as I use a screen reader. It’s like they’re magic rocks. I guess they stabilize ph and kh…there’s a few red flags now that I’m researching a bit. Who’d a thought you’d need to research into what a rock is? Ha. I have no clue what they’re made of. I do know they fizzed like alkaseltzer for over an hour

Hey @Aquaforest whats the deal here? Are these rocks made from cement? The website also states “AF ROCK MAY BE ALSO USED IN FUNCTIONING TANKS”, but doesn’t state with caution or anything,

AF Rock - Aquaforest

AF Rock by Aquaforest: natural and aesthetic rocks for aquarium arrangements that create a stable and attractive environment for corals and fish. Natural and safe for marine organisms composition.

aquaforest.eu

 

[A_Blind_Reefer]

I did find an old reef builders article that states made in Poland with a white cement like substance……you know, they should tell you this stuff! I mean if a small amount (22lbs) in a sump can increase alkalinity over 2 dkh (almost instantly) with a total liquid volume of around 200 gallons it could be detrimental in smaller volumes. As it is an over 2dkh swing isn’t great and historically it may take a week or two to show any signs of stress…and I’m too visually impaired to notice now. I’m thinking this was a big mistake on my part, I just wanted a couple rocks doh

AF Rock is Aquaforest’s man-made reef rock | Reef Builders | The Reef and Saltwater Aquarium Blog

With live rock shipments few and far between these days, manufacturers and hobbyists have had to turn to mined or man-made alternatives instead. And Aquaforest is one such rock provider with their…

reefbuilders.com

 

[A_Blind_Reefer]

So yeah, it’s like close to 2am now. With the Kalk and calcium reactor off, calcium has dropped off. Alkalinity has finally stopped climbing. I will have to manually dose calcium to bring it back up and maybe bring the calcium reactor and kalk back online after noon if alkalinity has dropped. Never would I ever have thought that adding some rock to a sump could cause such a swing, I’m still baffled.

 

[taricha]

I'd guess most man- made rocks have something very similar to cement in them.
Curing can be very slow. I messed around with chunks from some purple painted stuff once, that had been in a petco fish tank. When I broke the chunk off and put it in my sample container, the pH of the saltwater went way up.
I guessed that breaking the rock exposed the less-cured interior. Part of the curing process for cement is to absorb CO2 - so that'll raise pH. I don't know details on what cement does that'd raise Alk.

 

[Randy Holmes-Farley]

I don't know details on what cement does that'd raise Alk.

A major component in Portland cement before it is heated in a furnace is limestone. Heating converts it into calcium oxide, which is also how kalkwasser powder is made. That calcium oxide proceeds on curing to make other compounds, and is likely how both pH and alk are raised in cement that is not fully cured.

 

[A_Blind_Reefer]

I'd guess most man- made rocks have something very similar to cement in them.
Curing can be very slow. I messed around with chunks from some purple painted stuff once, that had been in a petco fish tank. When I broke the chunk off and put it in my sample container, the pH of the saltwater went way up.
I guessed that breaking the rock exposed the less-cured interior. Part of the curing process for cement is to absorb CO2 - so that'll raise pH. I don't know details on what cement does that'd raise Alk.

This is making more sense to me now. Ph did climb as well but not as drastically as kh. The high for the day is typically 8.3 and it had hit 8.55. Kalk is programmed to shut off at 8.5 just in case. I wasn’t too concerned as I checked the probe with 7.0 solution and it was reading a little over at 7.14 so I chalked that up to drift but it continued to rise a little after lights out. I find it a little disturbing that there is no mention of these effects at all whatsoever with this product (that I could find, I am blind as a bat though). If you’re starting a tank from scratch it’s no biggie. If you have a mature tank and just filling up a sump compartment, it’s a bit concerning.

 

[A_Blind_Reefer]

A major component in Portland cement before it is heated in a furnace is limestone. Heating converts it into calcium oxide, which is also how kalkwasser powder is made. That calcium oxide proceeds on curing to make other compounds, and is likely how both pH and alk are raised in cement that is not fully cured.

Could this explain the alkaseltzer effect (fizziness for over an hour)?

 

[A_Blind_Reefer]

I can’t read graphs but I can hear the data points. I copied the alk and ca graphs if anyone’s curious.

The alk skyrockets while ca drops (after I shut everything down).

 

[Randy Holmes-Farley]

Could this explain the alkaseltzer effect (fizziness for over an hour)?

It was bubbling in tank water?

 

[A_Blind_Reefer]

It was bubbling in tank water?

Yes profusely

Edit. I just thought it might be the pumice like material that someone on YouTube said was inside

 

[Randy Holmes-Farley]

I don't know what that would be that is consistent with a pH rise. CO2 release would lower pH. Trapped air would be a minor process.

 

[Garf]

Yes profusely

Edit. I just thought it might be the pumice like material that someone on YouTube said was inside

Don't they cure these things? Cement takes about a month in freshwater with lots of waterchanges to become usable, normally.

 

[A_Blind_Reefer]

Don't they cure these things? Cement takes about a month in freshwater with lots of waterchanges to become usable, normally.

You know, I’m an artificial rock dummy. I have no clue about these things. I didn’t even know they were man made, or colored when I ordered them. I just thought they were typical dry rocks

 

[Garf]

You know, I’m an artificial rock dummy. I have no clue about these things. I didn’t even know they were man made, or colored when I ordered them. I just thought they were typical dry rocks

Well to be honest I've never used air cured cement in a tank, perhaps given enough time it becomes usable as it reacts with CO2 or something, I don't know.

 

[twentyleagues]

I am with @Garf here. I had made aggracrete in the past and the curing process is exhausting. I doubt any company making these things is going to go through a process that long. They probably build it, muriatic acid bath it, freshwater rinse it, stain it and send it out as good. I tried that my self and while it did cut down on the "cure" time it didnt solve the issue of it leaching for a prolonged time.

 

[A_Blind_Reefer]

So with all dosing switched off (kalk drip and calcium reactor) since yesterday just after 6pm my tank has dropped 0.45 dkh and 21 ppm calcium. This seems to be quite bit off from the historical ratio. I’m guessing the rock is still adding alkalinity, just a little slower than is consumed. I know my tank consumes over 2.8 dkh per day, how much more I don’t know since I switched away from two part.

 

[Miami Reef]

It sucks when a simple rock throws out the stability your worked hard for. Who would expect a small rock to add alkalinity? So frustrating. I feel for you.