Does calcium go down when doing water changes?

luffy

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Helloo everyone, question.

So I have been doing a lot of water changes for my 24 gallon because of nitrate levels being way above 40 ppm, im finally at 40 ppm and want to do another 50 since its been 3 weeks of not doing a water change but i had my water tested and they had said my calcium was at 511.

20260129_221343_2E7360BE-D550-4849-A44D-1AD6C2C05C94.png
He didnt get to magnesium at my lfs but it doesnt bother me much. I believe my levels are coming down but will it effect my calcium if im doing so many? The past weeks before not doing water change i have been doing 50-30% weekly , i let it settle because of me being worried of my water and adding too much new water, but i have a porcupine puffer (i know im upgrading to a 75 sooner or later once i have funds and yes i know thats not enough gallons for him) also a chalk bass and gsp and purple tip anemone, some crabs and naserius snails. What do you guys think?
 

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I'm going to suggest that you rehome the Puffer, it's not a good fit for a 24 gallon, or really even a 75, especially if you don't know if/when you'll be getting a larger tank.

As for your parameters, I'm a little skeptical of those numbers. What salt mix are you using, and what did your shop use to test your water?
 

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Calcium will go down with a water change if the calcium in the new water is lower than the current water.
ie if your 24 gallon tank is 500 ppm calcium and you change 10% with new water that is 400 ppm calcium the resulting calcium will be 490 ppm
 

Mr. Mojo Rising

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I think the high nitrate is more based on the tank being overstocked and the filtration unable to keep up, water changes are the lifeline until you get that puffer out of the tank. Also skeptical of the phosphate reading, what test kits are you using? Calcium of 511 is not a concern to me.
 

Randy Holmes-Farley

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I agree that the calcium is fine, as is 40 ppm nitrate, and I would not do a water change just because of either one.


  • 4. What targets seem reasonable? Of course, that depends on all the other factors at play, such as types of corals, availability of ammonia, particulate foods, etc. However, for a mature mixed reef, this would be how I personally would run it:
    • Let nitrate float between 5 ppm and 50 ppm. I’d use gentle export in this range, such as growing macroalgae.
    • Above 50 ppm, I’d begin to focus more on reducing it, by organic carbon dosing, turf or macroalgae, etc.
    • Below 5 ppm, I’d begin to dose ammonia or feed more. The target level might drop lower if dosing ammonia, just like the heavy in/heavy out scenario where nitrate may not be as needed.
    • Let phosphate float between about 0.06 ppm and 0.3 ppm. This range is higher than I’ve recommended in the past. I’d use gentle export in this range, such as growing macroalgae.
    • Above about 0.3 ppm, I’d begin to focus more on reducing it, by turf or macroalgae, or a binder such as GFO or lanthanum (has its own risks to tangs). If a binder: GO SLOW. Turf and macroalgae will typically be slow enough.
    • Below 0.06 ppm, I’d begin to dose sodium phosphate or feed more to get the level up.
 
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luffy

luffy

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I'm going to suggest that you rehome the Puffer, it's not a good fit for a 24 gallon, or really even a 75, especially if you don't know if/when you'll be getting a larger tank.

As for your parameters, I'm a little skeptical of those numbers. What salt mix are you using, and what did your shop use to test your water?
I understand your suggestion, were collecting better supplies for our tank upgrade. We have a 75 gallon that we’re going to build a better setup with. It was the second biggest tank we could purchase at our Lfs. The guy at our fish store i believe used a Api test kit, numbers might not be accurate. I had a lot of lfs test my water cuz one said i had no nitrates which i just didnt believe .
 
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luffy

luffy

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Calcium will go down with a water change if the calcium in the new water is lower than the current water.
ie if your 24 gallon tank is 500 ppm calcium and you change 10% with new water that is 400 ppm calcium the resulting calcium will be 490 ppm
Alright makes sense, thank youu
 

Gumbies R Us

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I understand your suggestion, were collecting better supplies for our tank upgrade. We have a 75 gallon that we’re going to build a better setup with. It was the second biggest tank we could purchase at our Lfs. The guy at our fish store i believe used a Api test kit, numbers might not be accurate. I had a lot of lfs test my water cuz one said i had no nitrates which i just didnt believe .
Yeah, I would ditch the api kits; those are known for not being accurate. Get yourself some Red Sea, Hannas or saliferts
 
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luffy

luffy

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I agree that the calcium is fine, as is 40 ppm nitrate, and I would not do a water change just because of either one.


  • 4. What targets seem reasonable? Of course, that depends on all the other factors at play, such as types of corals, availability of ammonia, particulate foods, etc. However, for a mature mixed reef, this would be how I personally would run it:
    • Let nitrate float between 5 ppm and 50 ppm. I’d use gentle export in this range, such as growing macroalgae.
    • Above 50 ppm, I’d begin to focus more on reducing it, by organic carbon dosing, turf or macroalgae, etc.
    • Below 5 ppm, I’d begin to dose ammonia or feed more. The target level might drop lower if dosing ammonia, just like the heavy in/heavy out scenario where nitrate may not be as needed.
    • Let phosphate float between about 0.06 ppm and 0.3 ppm. This range is higher than I’ve recommended in the past. I’d use gentle export in this range, such as growing macroalgae.
    • Above about 0.3 ppm, I’d begin to focus more on reducing it, by turf or macroalgae, or a binder such as GFO or lanthanum (has its own risks to tangs). If a binder: GO SLOW. Turf and macroalgae will typically be slow enough.
    • Below 0.06 ppm, I’d begin to dose sodium phosphate or feed more to get the level up.
So i have had my tank set up for about 8-7 months, so still new. Ideally i would like 10-20 ppm of nitrates and my phos sitting around 1, im still trying to understand phos since im pretty new and its my 2nd salt water tank i have had. I dont feel like stocking any more fish in this tank if anything corals like candy cane or blastos, easy corals. That’s ideally what i want and what i run on filtration is i have a small sump behind the tank with a sock with matrix, pad and then macro algae and it goes to a overhang filter, and thats it. I lose a lot of water but i top of the sump with freshwater.

I really like your parameters you recommend and i want to strive to those.
 
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luffy

luffy

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I understand your suggestion, were collecting better supplies for our tank upgrade. We have a 75 gallon that we’re going to build a better setup with. It was the second biggest tank we could purchase at our Lfs. The guy at our fish store i believe used a Api test kit, numbers might not be accurate. I had a lot of lfs test my water cuz one said i had no nitrates which i just didnt believe .
Yeah, I would ditch the api kits; those are known for not being accurate. Get yourself some Red Sea, Hannas or saliferts
Yeah i know , literally have some places i can get some hannas but right now thats what i have been using. I think i want to get a hanna nitrate and then phos, first the when i can afford i want to get the calcium.
 

Randy Holmes-Farley

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So i have had my tank set up for about 8-7 months, so still new. Ideally i would like 10-20 ppm of nitrates and my phos sitting around 1, im still trying to understand phos since im pretty new and its my 2nd salt water tank i have had. I dont feel like stocking any more fish in this tank if anything corals like candy cane or blastos, easy corals. That’s ideally what i want and what i run on filtration is i have a small sump behind the tank with a sock with matrix, pad and then macro algae and it goes to a overhang filter, and thats it. I lose a lot of water but i top of the sump with freshwater.

1 ppm phosphate may be fine, but it's very unusual as an intended target. Is that really what you mean?
 
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luffy

luffy

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So i have had my tank set up for about 8-7 months, so still new. Ideally i would like 10-20 ppm of nitrates and my phos sitting around 1, im still trying to understand phos since im pretty new and its my 2nd salt water tank i have had. I dont feel like stocking any more fish in this tank if anything corals like candy cane or blastos, easy corals. That’s ideally what i want and what i run on filtration is i have a small sump behind the tank with a sock with matrix, pad and then macro algae and it goes to a overhang filter, and thats it. I lose a lot of water but i top of the sump with freshwater.

1 ppm phosphate may be fine, but it's very unusual as an intended target. Is that really what you mean?
I would like to target something around there, like i said i don’t really understand what is a good phos level and what to be striving for .
 

Randy Holmes-Farley

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I would like to target something around there, like i said i don’t really understand what is a good phos level and what to be striving for .

I'd be surprised if you found ANY other reefer at Reef2Reef who actually has a target of 1 ppm phosphate or higher. Some have reef tanks that high for various reasons, but generally, even among those folks, its not because they targeted that level.

You will find lots of folks with targets in the 0.1 ppm phosphate range, and some much lower.
 
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luffy

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I would like to target something around there, like i said i don’t really understand what is a good phos level and what to be striving for .

I'd be surprised if you found ANY other reefer at Reef2Reef who actually has a target of 1 ppm phosphate or higher. Some have reef tanks that high for various reasons, but generally, even among those folks, its not because they targeted that level.

You will find lots of folks with targets in the 0.1 ppm phosphate range, and some much lower.
Mmm i see, i would like to see if any other lfs can test my phos cuz i just had one of my lfs use a api and i know it might be a bad reading. Thank you so much randy, how would you tackle phos if they are where mine are?
 

Randy Holmes-Farley

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Mmm i see, i would like to see if any other lfs can test my phos cuz i just had one of my lfs use a api and i know it might be a bad reading. Thank you so much randy, how would you tackle phos if they are where mine are?

If it was me, I'd ignore that result for now.

Do you have plans to get a test yourself, or rely on lfs (cheaper, of course, but inconvenient and potentially risky).
 
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luffy

luffy

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Mmm i see, i would like to see if any other lfs can test my phos cuz i just had one of my lfs use a api and i know it might be a bad reading. Thank you so much randy, how would you tackle phos if they are where mine are?

If it was me, I'd ignore that result for now.

Do you have plans to get a test yourself, or rely on lfs (cheaper, of course, but inconvenient and potentially risky).
I really want my lfs to use better testers near me, literally went to some sacramento stores and they all used api tests , ill ignore my phos and focus my attention on nitrates and calcium, i was thinking of getting more corals that can start consuming some calcium and nitrates but i might just hold off on it andset my 75g, i might just invest in some hannas
 

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