Rising Alkalinity

Alan M

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I was directed to post here from one of the other threads by a member with one of my questions. The first question was about RTN/STN which led to my rising alkalinity levels. The system is 9 months old. Started on dry rock. Seeded and a 8 week lightless cycle. I then added fish and started ramping up lights. I initially had some algae and Dino issues so I waited to add coral. Once those issues were resolved, I added coral at about 5 months. Through that 5 months I was having to dose Po4 and No3 to keep levels up. It finally started to settle in and I didn’t have to dose. Started with some lps and they did fine. Then added a green slimer and Millie, those did good. Now that I’ve started to add some more picky sps I’m having trouble with burnt tips and then totally dying. Which led to this alk issue. I’m testing alk, calc, and mag with trident (also Red Sea to verify results). Po4 with Hannah and No3 with salifert. I’m using fritz blue box salt. For example, it will raise from 9.7 to 9.8 in a 24 hr period. Which isn’t bad but it consistently rises day after day. I’d prefer to be around 8. I have 4 hydra 64’s for lighting. 360 par at the top of my rocks. 200 on the sand bed. I have an 8 stage RODI system and make sure water is always 0 TDS. I have well water so I don’t condition the water. I have never dosed alk, cal or mag. I have sent in an ATI icp and things looked good other than some elevated metals. Have a fresh ATI icp on the way to Germany right now.
Water changes every 3 weeks. 180g and change 50g.
Ph- 7.95 - 8.2
Salinity- 1.025
Alk- 9.98
Calc- 454
Mag- 1330
No3- 5
Po4- .15
Temp- 78
All of these parameters are staying very stable accept alk. I’ve done a lot of searching and reading on the issue and seen a reply of a similar post from Randy Holmes Farley. I didn’t want to reply and highjack the thread tho. The 4 options were-
1) water changes with a lower alk mix (you can make it as low as you want)
2) slowly adding acid
3) increase organisms in the tank that consume calcium and alkalinity.
4) try removing the sand or replacing it with something else.
Option 1 seems the most viable to me, although I don’t know how to do a water change with a lower alk mix making it as low as I want. That may lower the alk but not getting to the root of the problem and why it’s rising? And I’d rather not add more coral with the chance it will die. Any help would be greatly appreciated. Thank you. I will attach a few pics of coral problems.

AAA97F0E-8EA1-433B-9D6E-12E0F2609DF1.jpeg 4038A031-66A5-43BB-9BF6-8F60F604D8DC.jpeg DFB73C62-1518-4C94-8C9F-AB2889352F2B.jpeg CEE0B3D4-4660-4010-955A-0ACEF4D9E947.jpeg
 
REEFTIDE

Randy Holmes-Farley

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FWIW, the RTN/STN cannot raise alkalinity, but it likely reduces the demand for alk.

Nitrate dosing adds alk (are you still dosing any?), which could be more than the demand at the moment if you are dosing any.
 
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Alan M

Alan M

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FWIW, the RTN/STN cannot raise alkalinity, but it likely reduces the demand for alk.

Nitrate dosing adds alk (are you still dosing any?), which could be more than the demand at the moment if you are dosing any.
Thank you for the reply. I am not dosing nitrate. I haven’t dosed anything in 2 months. Nitrate stays a steady 5.
 
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Miami Reef

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Correct. I mixed up a gallon and tested it. It read 9.2 freshly mixed.
I looked it up and the label says alk is from 8-9 which seems right.

Which metals are elevated? Why would they be elevated if your TDS is 0?

I’m thinking your TDS meter isn’t actually 0 and you are slowly adding metals (maybe also alkalinity?)

The bolded is my hypothesis and a wild guess. Don’t take it to heart just yet. @Randy Holmes-Farley
What do you think about that?

OP: please let me know which metals are elevated.
 
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Alan M

Alan M

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I looked it up and the label says alk is from 8-9 which seems right.

Which metals are elevated? Why would they be elevated if your TDS is 0?

I’m thinking your TDS meter isn’t actually 0 and you are slowly adding metals (maybe also alkalinity?)

The bolded is my hypothesis and a wild guess. Don’t take it to heart just yet. @Randy Holmes-Farley
What do you think about that?

OP: please let me know which metals are elevated.
The raised elements-
Copper- 5.08
Zinc- 11.07
Tin- 9.73
 
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Alan M

Alan M

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It doesn’t make sense why Alkalinity is rising despite not dosing anything. Do you have a list of everything you are/have been adding to the tank?

Also, it’s just the SPS that are dying? Not the LPS, right?
All LPS are doing fine and some sps. I have a Millie that’s doing great. The only thing I put in the tank are sheets of Nori, flakes, brine shrimp, coral feast 1x week and AB+ 1-2x a week.
 

Randy Holmes-Farley

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Alan M

Alan M

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Alk can slowly rise in a tank with very low to no demand.

it happens from falling nitrate levels, and from very slow dissolution of sand and rock.
It is a newer system with mostly frags. Lights just ramping up but I will attach a few pictures. I test alk daily at the same time. Before some sps started dying I had a fair amount of frags but it never stopped it from rising. How do I lower alk in my fresh salt mix? Then I need to tackle the RTN/STN issue.
 

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Randy Holmes-Farley

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Thank you. How do you recommend keeping the alk level stable once lowered? More frequent water changes to keep it from creeping up over time until there’s enough coral to start using it?

Once the corals are back and growing again the issue should disappear. Adding more hard corals will also do it.
 
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Alan M

Alan M

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Randy Holmes-Farley

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Ok, thank you! Any recommendations on fixing the RTN/STN issue? I greatly appreciate it.

No, sorry. Not sure what is causing it. I wouldn't be sure those metals are an issue, but reducing them with a metal binder like polyfilter/metasorb/cuprisorb may be a thing to try.
 

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