Why do my numbers fluctuate so much?

[aquaman99]

Before I run to the store and buy everything under the sun to dose, maybe a veteran reefer can spot the issue. Here have been my numbers for CA, MG, KH for the past 7 days. The only thing that has changed in the tank is that I added 2 seahorses four days ago and increased the amount of food I feed per day because of it. I stopped dosing everything 10 days ago. I was dosing Polyp Labs Nano One. All tests were taken within 90 minutes of the same time every day.

CA: 430 430 420 420 400 410 260 (Not a typo. Checked 3 times)
MG: 1320 1425 1365 1365 1110 1245 1230
KH: 12.8 10.9 8.0 8.9 8.3 7.7 7.5

I hope that chart is easy to read. Any advice or help is welcome. I am at a loss. A triton is on the wish list but it might be about 6 months (Christmas) before I get it. Unless I win the FB @Bulk Reef Supply raffle.

 

[aquaman99]

Also if it helps, my NO3 has stayed steady all 7 days between 2 and 5 ppm so I call that 3.5ppm. My PO4 has been 0, based on API kit, all 7 days just like my NH4 and NO2.

 

[Dom]

1. How big is your tank?
2. Do you have automatic top off?

Smaller tanks tend to show bigger swings.

As an example, when you test salinity, you are testing the ratio of salt to water. While water evaporates, salt does not. So as water volume goes down (through evaporation), the ratio of salt to water goes up.

We keep salinity stable by having auto top off, so that water volume doesn't fluctuate, thereby keeping salinity stable.

I believe the same holds true for elements like calcium and magnesium.

Hope this helps.

Dom

 

[aquaman99]

1. How big is your tank?
2. Do you have automatic top off?

Smaller tanks tend to show bigger swings.

As an example, when you test salinity, you are testing the ratio of salt to water. While water evaporates, salt does not. So as water volume goes down (through evaporation), the ratio of salt to water goes up.

We keep salinity stable by having auto top off, so that water volume doesn't fluctuate, thereby keeping salinity stable.

I believe the same holds true for elements like calcium and magnesium.

Hope this helps.

Dom

The tank is 65g with a 20g sump holing about 10ish gallons of water.

I do not have auto top off. I add a cup of RODI every day or two depending on if the sump level goes down.

My salinity always stays at .025 with a refractometer.

 

[Dom]

The tank is 65g with a 20g sump holing about 10ish gallons of water.

I do not have auto top off. I add a cup of RODI every day or two depending on if the sump level goes down.

My salinity always stays at .025 with a refractometer.

I would encourage you to get an auto top off. It doesn't have to be anything fancy. I have a gravity fed setup. It is my 40 gallon water storage tank with 1/4 inch tubing going to a float valve in my sump.

 

[BeejReef]

I agree an ATO is really a godsend. I fought it. Finally gave in. It is so worth it.

Beyond that, the big question is your test kits. What brand are you using for each parameter? How old are they? How old is your tank? How experienced are you in using them? Young tank swings harder. New reefer hasn't always settled into a stable routine. Both of those observations describe me as well

So, something is off with your calcium test. Beyond that, if you look at the trends, it's about what you would expect. You're consuming calcium, alkalinity, and magnesium. If those figures are from every other day, the consumption is in the ballpark.

If you figure that any test kit can vary by 10%, user perception, and the fluctuations in salinity good for another 10%, chances are there's nothing to see here.

One oddity is your initial DKH reading of near 13. If that was an accurate reading and not an outlier, you might expect a little instability as the tank kind of falls down to a more sustainable level.

Also, how solid is your return pump? My first kind of ran in surges... real strong for a few days, then kinda weak, then kinda strong.. lol. It wasn't a huge effect, but the DT volume/height would vary by 1/4-1/2 inch. Topping off in the sump to a set level, my salinity would swing along with the return pump's moods.

 

[aquaman99]

I agree an ATO is really a godsend. I fought it. Finally gave in. It is so worth it.

Beyond that, the big question is your test kits. What brand are you using for each parameter? How old are they? How old is your tank? How experienced are you in using them? Young tank swings harder. New reefer hasn't always settled into a stable routine. Both of those observations describe me as well

So, something is off with your calcium test. Beyond that, if you look at the trends, it's about what you would expect. You're consuming calcium, alkalinity, and magnesium. If those figures are from every other day, the consumption is in the ballpark.

If you figure that any test kit can vary by 10%, user perception, and the fluctuations in salinity good for another 10%, chances are there's nothing to see here.

One oddity is your initial DKH reading of near 13. If that was an accurate reading and not an outlier, you might expect a little instability as the tank kind of falls down to a more sustainable level.

Also, how solid is your return pump? My first kind of ran in surges... real strong for a few days, then kinda weak, then kinda strong.. lol. It wasn't a huge effect, but the DT volume/height would vary by 1/4-1/2 inch. Topping off in the sump to a set level, my salinity would swing along with the return pump's moods.

I will look into an ATO but I only have space for maybe a 3gal container. IDK how much help that is really going to be? And it would have to be lower than the tank. I don't have any space above the tank or higher than the tank. So gravity fed seems out of the question.

Salifert is the brand I use for my CA, MG, and KH. The tank is almost 5 months old. I have 5 months experience using them. I had no idea that the test kit could very that much and with a gallon of evaporation factored in that the values could be effected by so much. I can see a pattern with the CA for sure but the MG seemed to be random until I did the math with the new found and explained variance. When I was dosing my KH was always in the high 12s. So the drop could be from stopping the dosing.

I bought the biggest return pump the store had when I set up my tank. I was told it would be more than enough. I do notice that the return comes in waves every few minutes(under 5). So maybe there is some surges every few minutes. If I top off the DT then the sump floods. So I have learned to top off the sump to a specific level and then nothing floods.

 

[Big E]

How are you supplementing alk and calcium? What dosing did you stop?

 

[rsumner]

+1 on the ATO to reduce one of the variables in your tests. You mentioned that you stopped dosing 10 days ago and your readings seem to show that with consistent decline in CA and KH readings. I don't see a "problem". Check out this BRS video to help you understand the dynamics of the whole topic of accuracy and consistency of testing results: https://www.bulkreefsupply.com/vide...-skills-on-your-reef-tank-brstv-investigates/

 

[vetteguy53081]

I would start with a water sample to a trusted LFS and see what readings they get and also for comparison
Temperature also affects some readings as does lighting.

 

[joeyamador]

I had a fluctuating issue actually recently and found out my trident apparently changed my dosing schedule and I had a lot of my solution precipitating out because they were ALL dosing at the same time...And also don't forget number chasing in MY opinion will drive you mad!!!! I have a 90 gallon that the magnesium will not stay where I want it but its thriving.. I gave up and now things seem to be happier and thriving.. does your dosing schedule have a waiting period in between solutions? Biggest issues my clients have when major swings are concerned is precipitation.. at the same time I have had weird growth periods where my coraline or clams will uptake ther crap out of everything then stall slightly due to fast corrections (lack of stability).. or when You change water do you notice the larger swings? Could be something off with your salt if it is.. just a few thoughts.. I figure if we give you 100 ideas one will help lol.

 

[W1ngz]

The overall trend seems to be down. One weird Ca and Mg reading are the only things I see that really stand out. I can't help but wonder if these are testing errors. I'm forever forgetting which salifert tests need 1, 2 and 3ml, how many drops of this that and the other thing so no matter how familiar I am with the tests, I've disciplined myself to:

Always double check the salinity before doing other tests.
Always do the tests under the same light, in the same place, at about the same time of day.
Always flip to the directions page and follow them step by step.
Never run more than one test at a time.
Never have reagents in front of me for a test I'm not doing at that minute.

It stops me from becoming complacent and to make sure I don't wander off into some sort of testing trance and mess up an otherwise simple procedure. Also, I can't recall which test, but Salifert recently changed something and one of the reagents went from 8 drops to 10. Going from memory and not looking at the directions, I'd have missed that completely.

And yes, ATO, definintely.

 

[joeyamador]

The overall trend seems to be down. One weird Ca and Mg reading are the only things I see that really stand out. I can't help but wonder if these are testing errors. I'm forever forgetting which salifert tests need 1, 2 and 3ml, how many drops of this that and the other thing so no matter how familiar I am with the tests, I've disciplined myself to:

Always double check the salinity before doing other tests.
Always do the tests under the same light, in the same place, at about the same time of day.
Always flip to the directions page and follow them step by step.
Never run more than one test at a time.
Never have reagents in front of me for a test I'm not doing at that minute.

It stops me from becoming complacent and to make sure I don't wander off into some sort of testing trance and mess up an otherwise simple procedure.

And yes, ATO, definintely.

I purchased a box of 300 hypodermic needles for my wife when she test for me while I'm out of town and wrote on the plungers how much of each solution to simplify it for her.. speed it up too so I use them as well now lol.

 

[SMB]

There are lots of ways to hide a bigger reservoir for ATO. This is a 15 gal food safe container with Tunze ATO.
Also check your salt mix before doing a WC. Make sure it is delivering what is says it's parameters should be.
Finally get two BRS dosers and 1 gal slim containers. Set up with smart plugs and you can dial in run times on your phone.
You would be surprised how stable this will make your numbers.

 

[aquaman99]

WOW I got a lot of replies! I'm so excited. So many good ideas and so many helpful tips. I will be responding to your messages later today in more detail. Thank you all again for the help. I think I was expecting my numbers to be exact and I'm finding out testing just gives you a ballpark or a trend over time. I graphed my numbers in excel and I can visually see a downward trend and that really helped me make sense of what I felt was up and down numbers.

 

[blasterman]

Do you want to know the best way to test Ca and magnesium in a tank that doesn't have heavy SPS?

Answer: Don't, because it's a waste of time, and no testing instrument or kit you can afford is nearly as accurate as your ability to record it. Also, consumer grade reef salts will vary in terms of composition more than the accuracy of your test kits, so again, why bother?

Calcium and Magnesium do not vary in a reef tank unless (A) corals / coraline algae are consuming them (B) you are precipitating them out via ridiculous alk or kalk dosing. In a tank that's not stocked with fast growing montipora or wall to wall coraline calcium and mag will eventually deplete, but a glacial pace and should be remedied by even infrequent water changes. Basically you are doing the reef equivelant of 'Train Spotting' or snipe hunting.

Alkalinity on the other hand is worth checking for in a younger tank. Lots of organisms other than corals consume alkalinity and can cause rapid depletions and non linear consumption. More mature tanks will consume alk at a pretty consistent pace. Since alk can be replaced via a .99 cent box of grocery store baking soda and a 30 second check on any reef calculator web site it's a trivial issue to adjust. 'Buffer in a Bottle' sold at reef stores is almost a big a joke as cans of dehydrated water.

 

[aquaman99]

How are you supplementing alk and calcium? What dosing did you stop?

I am using and was using 1ml of Polyp Lab One per day.

I don't see a "problem".

I got it so stuck in my head that the ocean perameters never change that I thought 1 number up or down was a lot. That's why I was so confused why sometimes it went up and sometimes it went down. I was only looking at the previous result not the string of results as a whole.

I would start with a water sample to a trusted LFS and see what readings they get and also for comparison
Temperature also affects some readings as does lighting.

I am considering doing just that today. my local LFS always offers but I never take them up on it. Well today I will. Especially since I will test once before I leave and once when I get home and see how they all compare.
Also, I did lower my temp from almost 77 to 74 within a 2 day span so maybe that did affect my last 2 results.

And also don't forget number chasing in MY opinion will drive you mad!!!! I gave up and now things seem to be happier and thriving.. does your dosing schedule have a waiting period in between solutions? Biggest issues my clients have when major swings are concerned is precipitation.. at the same time I have had weird growth periods where my coraline or clams will uptake ther crap out of everything then stall slightly due to fast corrections (lack of stability).. or when You change water do you notice the larger swings? Could be something off with your salt if it is.. just a few thoughts.. I figure if we give you 100 ideas one will help lol.

I was like I said before, thinking that if for example it says to be within a 100+- of 1350 then the number itself was irrelevant in that range as long as it didnt flux more that 3+-. Again, that was me overreacting that the ocean never fluctuates. Side note about growth, I have about 20 diff types of zoas and they all grow another head or two every 4ish days but they never open. I guess this is an example of them growing but then stalling? I just tested my source water(the mix I create with my salt and my RODI.) My readings were: CA 390, MG 1110, and KH 10.9. So I can see already without dosing the Polyp Lab One that my numbers are not even where I am used to them being stableish. Stable as far as what I have been used to the past 4 months has been CA 420-430, MG 1320-1370, and KH 10-12.

The overall trend seems to be down. One weird Ca and Mg reading are the only things I see that really stand out. I can't help but wonder if these are testing errors.
And yes, ATO, definintely.

Ok Y'all talked me into an ATO lol. Enough people have said it... I'll get one.

There are lots of ways to hide a bigger reservoir for ATO.
Also check you salt mix before doing a WC. Make sure it is delivering what is says it's parameters should be.
Finally get two BRS dosers and 1 gal slim containers. Set up with smart plugs and you can dial in run times on your phone.
You would be surprised how stable this will make your numbers.

I like how you hide yours! I think I might do something very similar!!! I posted my source water test results as a reply above. This was a good idea. It was not the same as the side of the container said it would be. I plan to get a trident with an Apex set up hopefully at Christmas or before. Apex does not mess around on their pricing!

 

[vetteguy53081]

I am using and was using 1ml of Polyp Lab One per day.


I got it so stuck in my head that the ocean perameters never change that I thought 1 number up or down was a lot. That's why I was so confused why sometimes it went up and sometimes it went down. I was only looking at the previous result not the string of results as a whole.


I am considering doing just that today. my local LFS always offers but I never take them up on it. Well today I will. Especially since I will test once before I leave and once when I get home and see how they all compare.
Also, I did lower my temp from almost 77 to 74 within a 2 day span so maybe that did affect my last 2 results.


I was like I said before, thinking that if for example it says to be within a 100+- of 1350 then the number itself was irrelevant in that range as long as it didnt flux more that 3+-. Again, that was me overreacting that the ocean never fluctuates. Side note about growth, I have about 20 diff types of zoas and they all grow another head or two every 4ish days but they never open. I guess this is an example of them growing but then stalling? I just tested my source water(the mix I create with my salt and my RODI.) My readings were: CA 390, MG 1110, and KH 10.9. So I can see already without dosing the Polyp Lab One that my numbers are not even where I am used to them being stableish. Stable as far as what I have been used to the past 4 months has been CA 420-430, MG 1320-1370, and KH 10-12.


Ok Y'all talked me into an ATO lol. Enough people have said it... I'll get one.


I like how you hide yours! I think I might do something very similar!!! I posted my source water test results as a reply above. This was a good idea. It was not the same as the side of the container said it would be. I plan to get a trident with an Apex set up hopefully at Christmas or before. Apex does not mess around on their pricing!

yes , that lower temp will have a big impact and even affect salinity

 

[Big E]

Your'e dosing 1ml of alk/calc solutiion.............that's nothing.

Your alk and calc is going down because you aren't dosing enough. The livestock is using this as they grow. Up the dosage until the alk and calc tests level off and stay the same.

 

[Randy Holmes-Farley Verified Community Expert]

Some of the numbers the op posted are definitely error. Magnesium drops less than 2 ppm per day, assuming salinity is constant. Never more. The calcium dropping 400 to 260 is also error.