Alk rising, calcium same, just started dosing Mg

Gophish1982

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So I’m trying to better understand how these parameters affect each other and why some of my corals get unhappy.

I currently dose ESV 2 part. I thought I had found my sweet spot on the dosing. I have a 100g tank and I was dosing 38mL of each part and things were staying stable (Alk 8.5, Ca 440, Mg 1350). After I figured out the 38mL I was checking Alk and Ca pretty regularly for a while but not the Mg.

A couple weeks ago I discovered that my Mg had gone below 1200. I was under the impression that the ESV included Mg supplementation but I guess I was wrong, or that my tank is using more then the ESV was able to provide. So I started dosing the recommended 150mL/day to increase Mg by 10ppm each day. I wanted to get it up to 1400 and it took over 2 weeks, and almost half the gallon of ESV Mg. I had also started dosing 4mL of tropic Marin trace elements during that time because it was suggested that I was deficient on them based on an ICP test I shared here. During all this new dosing, many of my SPS corals that I never saw showing any PE were starting to come out really nicely. I once again thought I had found my sweet spot! I stopped with the Mg dosing after it got to 1400 and it has been holding steady in the high 1300s. I continued with the trace elements daily but then I started to see my SPS not opening and started to wonder if maybe I was over doing the trace. I noticed my PO4 had gotten back up to .2 which I thought I had taken care of by carbon/bacteria dosing before I started with the Mg/trace dosing. My Alk/Ca/Mg we’re still reading consistent until last week when Alk began to climb from 8.5 to 9.8 over 7 days. The only change I made at that particular time was going from 4mL of each trace daily down to every other day, and resuming my NoPox/microbacter7 doses I had cut in half when my PO4 was in an okay spot.

What I’m really trying to get down to here is why is my Alk rising when I’m adding the same amount of 2 part? Ca and Mg are stable. I’m pretty sure my SPS is closed up because of my PO4 rising again. Could this cause the tank to not use as much Alk? I thought Alk and Ca were consumed in the same ratio in general, so why wouldn’t Ca be also rising? How does raising Mg affect my Alk/Ca consumption? Does making adjustments to the carbon/bacteria dosing to control PO4 have any affect on Alk/Ca/Mg? Everything was stable when I was doing the carbon/bac dosing before.
 

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So I’m trying to better understand how these parameters affect each other and why some of my corals get unhappy.

I currently dose ESV 2 part. I thought I had found my sweet spot on the dosing. I have a 100g tank and I was dosing 38mL of each part and things were staying stable (Alk 8.5, Ca 440, Mg 1350). After I figured out the 38mL I was checking Alk and Ca pretty regularly for a while but not the Mg.

A couple weeks ago I discovered that my Mg had gone below 1200. I was under the impression that the ESV included Mg supplementation but I guess I was wrong, or that my tank is using more then the ESV was able to provide. So I started dosing the recommended 150mL/day to increase Mg by 10ppm each day. I wanted to get it up to 1400 and it took over 2 weeks, and almost half the gallon of ESV Mg. I had also started dosing 4mL of tropic Marin trace elements during that time because it was suggested that I was deficient on them based on an ICP test I shared here. During all this new dosing, many of my SPS corals that I never saw showing any PE were starting to come out really nicely. I once again thought I had found my sweet spot! I stopped with the Mg dosing after it got to 1400 and it has been holding steady in the high 1300s. I continued with the trace elements daily but then I started to see my SPS not opening and started to wonder if maybe I was over doing the trace. I noticed my PO4 had gotten back up to .2 which I thought I had taken care of by carbon/bacteria dosing before I started with the Mg/trace dosing. My Alk/Ca/Mg we’re still reading consistent until last week when Alk began to climb from 8.5 to 9.8 over 7 days. The only change I made at that particular time was going from 4mL of each trace daily down to every other day, and resuming my NoPox/microbacter7 doses I had cut in half when my PO4 was in an okay spot.

What I’m really trying to get down to here is why is my Alk rising when I’m adding the same amount of 2 part? Ca and Mg are stable. I’m pretty sure my SPS is closed up because of my PO4 rising again. Could this cause the tank to not use as much Alk? I thought Alk and Ca were consumed in the same ratio in general, so why wouldn’t Ca be also rising? How does raising Mg affect my Alk/Ca consumption? Does making adjustments to the carbon/bacteria dosing to control PO4 have any affect on Alk/Ca/Mg? Everything was stable when I was doing the carbon/bac dosing before.
By what method and what kits are you using to measure?
Alk and calcium work together in a sense that a balanced calcium and alkalinity additive is one that provides calcium and alkalinity in proportions that match that used by corals and other organisms to form calcium carbonate. Often overdosing is the risk we face when manually dosing. You therefore have to develop a balanced calcium and alkalinity supplementation regime starting insmall increments until you have a balanced number without chasing them.High calclium oftem lowers alk level.
 
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Gophish1982

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By what method and what kits are you using to measure?
Alk and calcium work together in a sense that a balanced calcium and alkalinity additive is one that provides calcium and alkalinity in proportions that match that used by corals and other organisms to form calcium carbonate. Often overdosing is the risk we face when manually dosing. You therefore have to develop a balanced calcium and alkalinity supplementation regime starting insmall increments until you have a balanced number without chasing them.High calclium oftem lowers alk level.
I was dosing by hand 1x per day when I first started dosing. That is when I figured out that 38mL was what was keeping my Alk/Ca/Mg stable. Then I got a Neptune Dos to automate it over the course of 24 hours. I regularly test with my Hanna Alk and pretty frequently double check with Salifert. They are always about .1 off with Hanna being the higher of the 2. Ca I check with Salifert and sometimes double check with RedSea, but I started to not trust the Red Sea. Mg is done with Aquaforrest. I also have a Trident running, but that’s a whole other issue I’m dealing with. My trident consistently reports 1.4 higher then my Hanna/salifert Alk, it often drifts lower on the Ca from the time I calibrate (right now reading 30 below salifert) but Mg is always really close. My Trident issues have been making me perform manual tests still once a day because I’m not trusting trident. But Alk is ALWAYS 1.4 higher then my other tests. So I don’t think this is a cause of testing errors. My Alk is definitely increasing. My Ca is either remaining the same or decreasing depending on if you trust my manual tests (saying it’s the same) or Trident (showing a slow downward trend).

I was discussing this at the LFS today as well, but unfortunately the employee only keeps fish, so she said her knowledge on dosing was limited. I thought I understood that Mg make the Alk/ca more available for consumption by coral, but would that cause my tests to pick it up more? And that still doesn’t explain why Alk is steadily rising and Ca is stable.

one thing I didn’t mention in my original post that might be asked is the salt I’m using. After a long time of using reef crystals, I switched to RedSea blue bucket a little while back because I wanted to keep my Alk around 8.5 and reef crystals mixes at 12 while RedSea is 7.5-8 I didn’t really see any changes to parameters when I switched. I do 10g changes once a week.
 
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vetteguy53081

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I was dosing by hand 1x per day when I first started dosing. That is when I figured out that 38mL was what was keeping my Alk/Ca/Mg stable. Then I got a Neptune Dos to automate it over the course of 24 hours. I regularly test with my Hanna Alk and pretty frequently double check with Salifert. They are always about .1 off with Hanna being the higher of the 2. Ca I check with Salifert and sometimes double check with RedSea, but I started to not trust the Red Sea. Mg is done with Aquaforrest. I also have a Trident running, but that’s a whole other issue I’m dealing with. My trident consistently reports 1.4 higher then my Hanna/salifert Alk, it often drifts lower on the Ca from the time I calibrate (right now reading 30 below salifert) but Mg is always really close. My Trident issues have been making me perform manual tests still once a day because I’m not trusting trident. But Alk is ALWAYS 1.4 higher then my other tests. So I don’t think this is a cause of testing errors. My Alk is definitely increasing. My Ca is either remaining the same or decreasing depending on if you trust my manual tests (saying it’s the same) or Trident (showing a slow downward trend).

I was discussing this at the LFS today as well, but unfortunately the employee only keeps fish, so she said her knowledge on dosing was limited. I thought I understood that Mg make the Alk/ca more available for consumption by coral, but would that cause my tests to pick it up more? And that still doesn’t explain why Alk is steadily rising and Ca is stable.

one thing I didn’t mention in my original post that might be asked is the salt I’m using. After a long time of using reef crystals, I switched to RedSea blue bucket a little while back because I wanted to keep my Alk around 8.5 and reef crystals mixes at 12 while RedSea is 7.5-8 I didn’t really see any changes to parameters when I switched. I do 10g changes once a week.
Mg can affect readings as will salinity if elevated.
I agree on the trident NOT being precise but close, Alk can rise due to quickly declining nitrate levels in your reef tank. Test your nitrate levels to see if this is the reason for the increase in alkalinity in your reef tank. if your nitrate level has fallen by 40 or more PPM, there can be an increase in alk by as much as 2.5 - 3.5 dKH.
 
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Gophish1982

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Mg can affect readings as will salinity if elevated.
I agree on the trident NOT being precise but close, Alk can rise due to quickly declining nitrate levels in your reef tank. Test your nitrate levels to see if this is the reason for the increase in alkalinity in your reef tank. if your nitrate level has fallen by 40 or more PPM, there can be an increase in alk by as much as 2.5 - 3.5 dKH.
Unfortunately that is not the case for me. My nitrates have never been higher then 25 which I wasn’t happy with and that was coupled with a phos reading of .2. That is when I decided to try the carbon/bacteria dosing. In about a week it lowered my phos to .06 and nitrate to 12. This was a few weeks ago. Alk remained stable during that time. My nitrates have stayed around there ever since, but my phos has gone back up to .2
 
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Unfortunately that is not the case for me. My nitrates have never been higher then 25 which I wasn’t happy with and that was coupled with a phos reading of .2. That is when I decided to try the carbon/bacteria dosing. In about a week it lowered my phos to .06 and nitrate to 12. This was a few weeks ago. Alk remained stable during that time. My nitrates have stayed around there ever since, but my phos has gone back up to .2
What test kits are you using?
 
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I would not assume the 1200 ppm magnesium is accurate unless the salinity was low.
@Randy Holmes-Farley I had always been told I should keep salinity around 1.025, but see many people also keep it at 1.026. My salinity can get low at times. Despite having this tank almost a year now I’m still not sure if I’ve ever really got my skimmer to run efficiently. It often fills my 1 gallon diy skimmate locker in a day which is replaced with Rodi. I’ve never seen my salinity below 1.023 though. I try to correct it with my weekly water changes. If I see my Mg deplete again, I will check salinity. I couldn’t confirm if this was the case when it happened recently because it’s not something I thought to check against.
Do you have any theories on why my Alk is climbing and Ca is remaining the same while I dose equal parts of ESV?
 
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What test kits are you using?
I test Alk with Hanna and Salifert. When I do both they are usually the same or with in .2dkh. For calcium I use salifert and Red Sea. Also usually very close. I test Mg with aquaforrest only. As I mentioned before though. Trident tests as well and Alk consistently reads 1.4 higher, I can’t ever trust Ca because it drifts down, Mg is almost always spot on to aquaforrest.
 
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What test kits are you using?
I probably should have added which test I use for nitrate since that was part of what you suggested. I started out using low range Red Sea until they started getting out of range results. I then switched to salifert and started reading 25 consistently. My LFS kept telling me they were 0 so I thought I had a bad salifert test so I got a Nyos and it too told me 25. Ultimately I stuck with Nyos because it has more color changes in the lower range then salifert. Now I’m always between the 5-12 colors.
 

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@Randy Holmes-Farley I had always been told I should keep salinity around 1.025, but see many people also keep it at 1.026. My salinity can get low at times. Despite having this tank almost a year now I’m still not sure if I’ve ever really got my skimmer to run efficiently. It often fills my 1 gallon diy skimmate locker in a day which is replaced with Rodi. I’ve never seen my salinity below 1.023 though. I try to correct it with my weekly water changes. If I see my Mg deplete again, I will check salinity. I couldn’t confirm if this was the case when it happened recently because it’s not something I thought to check against.
Do you have any theories on why my Alk is climbing and Ca is remaining the same while I dose equal parts of ESV?

A rise of specific gravity from 1.025 to 1.0264 (35 ppt, the worldwide ocean average) would boost magnesium from 1212 ppm to 1280 ppm, which again is the worldwide average.

The rise in alk from 8.5 to 9.8 dKH by dosing ESV two part would only be accompanied by a 9 ppm ruse in calcium, which is not reproducibly detected by test kit.
 
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Gophish1982

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A rise of specific gravity from 1.025 to 1.0264 (35 ppt, the worldwide ocean average) would boost magnesium from 1212 ppm to 1280 ppm, which again is the worldwide average.

The rise in alk from 8.5 to 9.8 dKH by dosing ESV two part would only be accompanied by a 9 ppm ruse in calcium, which is not reproducibly detected by test kit.
Thanks for that info. I literally came back to this thread to ask why after stopping my dosing to bring my Alk back down to where I want it, my Ca only went down by 10ppm. In my head I was expecting to see a bigger drop in Ca then just 10 as my Alk is now back down to 8.1, but you kind of answered that question.

I wonder if I can diverge slightly and ask about salinity since it was brought up. I have 2 coral shops here in Columbus. They both recommend different parameters which is pretty common in this hobby. One shop keeps their salinity at 1.025 and Alk 8-10, the other keeps theirs at 1.023 and Alk 10-12. I asked why and the only reason the employee really gave me was that the corals live just fine in 1.023 and it gives a buffer to keep it lower so it doesn’t accidentally creep up over 1.026 where it would be unsafe for the corals. I don’t know how I feel about that answer and maybe you could share your thoughts on it. That place actually calls themself a coral farm and they do have huge systems full of coral they grow out. The first store I mentioned mostly get their frags wholesale with the exception of some of their higher end SPS that they aquaculture in the shop.
 
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