Reef tank not using CA or ALK

[ReefersDelite]

Help R2R!!
For the life of me I cannot figure out why my aquarium will not consume ALK or CA.
Mildly stocked with mainly zoas and LPS but some SPS.
1 week testing resulted in no change except for MG. That went down some
Current and prior parameters are:
CA 430
ALK 9.0 ish
MG from 1305 to 1215

Using Salifert tests
AIO 45 gallon no sump - 2 AI Primes - Octo 90 HOB skimmer

 

[Larry L]

Are you doing water changes? It's possible the new water is replenishing whatever calcium and alk are being consumed.

It's also possible that the amount of consumption is small enough to be within the accuracy range of the test kit, or in the range of measurement error.

 

[ReefersDelite]

Are you doing water changes? It's possible the new water is replenishing whatever calcium and alk are being consumed.

It's also possible that the amount of consumption is small enough to be within the accuracy range of the test kit, or in the range of measurement error.

Yes. Weekly water changes but I should be seeing some decline. Zero changes except in MG in a week.

 

[malacoda]

You say you're lightly stocked.

A fair amount of LPS are slow-growing, which means your weekly water changes could be replenishing the loss before you have a chance to see any real change.

How long have your SPS been in the tank ... and do you see white tips on them? If they've been added recently and haven't kicked into growth-mode yet, then it is easily possible their consumption is also still very low as well ... too low to be noticeable on the test kit between your weekly water changes.

As long as your corals look healthy and are not receding, don't worry about it. (Besides, it's not like you can 'force' your corals to consume more alk and Ca. Maybe a bit by upping your light ... but then you run the risk moving too much too quick and bleaching them.)

Try to remain patient and just keep testing regularly -- at least once, or better yet twice a week. Could take a couple of weeks or even a couple of months. But when they do finally go into growth-mode, you will see the change in your test results.

 

[Larry L]

Weekly water changes but I should be seeing some decline.

Have you tested the newly-mixed water to see if it's mixing up higher than what's in your tank?

 

[ReefersDelite]

Have you tested the newly-mixed water to see if it's mixing up higher than what's in your tank?

Yes. Mixes at the levels it should

 

[ScottR]

At one point, I stocked mostly LPS and softies. I too had this “problem”. As I added more corals and inverts to my tank, I had to start doing more WC and dosing to replenish. To put it simply, there’s not enough demand from your tank inhabitants.

 

[SPR1968]

You don’t say how old the tank is, but if your not depleting foundation elements, your not depleting them and does it really matter ?

As your system and corals grow, just monitor and test and add the elements as required. If you don’t need any particular one don’t add it. Don’t think you need or should be adding anything unless you’ve tested and it’s needed.

If you want to increase coral growth you could maybe look at increasing the levels. I ran the Red Sea Accelerated growth program for over 12 months with alkalinity at around 12.6dKH with corresponding higher than ‘normal’ calcium and magnesium figures all to encourage growth, which certainly works, but it depends what your trying to achieve.

 

[ReefersDelite]

You don’t say how old the tank is, but if your not depleting foundation elements, your not depleting them and does it really matter ?

As your system and corals grow, just monitor and test and add the elements as required. If you don’t need any particular one don’t add it. Don’t think you need or should be adding anything unless you’ve tested and it’s needed.

If you want to increase coral growth you could maybe look at increasing the levels. I ran the Red Sea Accelerated growth program for over 12 months with alkalinity at around 12.6dKH with corresponding higher than ‘normal’ calcium and magnesium figures all to encourage growth, which certainly works, but it depends what your trying to achieve.

Tank is a little over 1 1/2 years. Just find it crazy that I’m not showing any usage but time will tell

 

[Steve Erekson]

Are you growing coralline?

 

[ianryd]

I have a "lightly stocked" lps & softie with a couple sps 75. The only thing it consumes is Alk, and at a very low rate. Like 1 dkh per week. My corals look happy and have good growth. I figure my water changes keep my levels stable and my system just has low requirements. If they start consuming more, Ill worry about that when it happens!

 

[blasterman]

The wrong assumption here is that the only source of calcium / alk in a tank is only what you put in via water changes or dosing / reactor because reef tanks are entirely closed loop. Not True. There are no boats that drive around the ocean dumping calcium chloride into the sea to keep corals alive.

If you have good bed of crushed coral and/or live rocks and healthy water circulation there will be a natural entropic conversion of calcium carbonate in the substrate to Ca ions available in the water column for coral . It's the same process that a calcium reactor uses, just far more diffuse, but it's there. C02 / carbonic acid suspended in the water will dissolve calcium carbonate and provide it for corals ( or clog your plumbing and force you to buy a water softner). The bigger the tank the more reaction there is, and hence another reason bigger tanks tend to be better for SPS growth. The 'buffering capacity' of crushed coral isn't a marketing term. It's a chemical process that also provides Ca for corals, albeit in small amounts

I've seen proof of this first hand and witnessed very healthy SPS tanks where the tank owner does not dose or run a reactor and only does sporadic water changes maybe one or twice a year. These tanks also had deep crushed coral beds, and excellent water circulation and air turnover. They also werent small.

 

[ScottR]

The wrong assumption here is that the only source of calcium / alk in a tank is only what you put in via water changes or dosing / reactor because reef tanks are entirely closed loop. Not True. There are no boats that drive around the ocean dumping calcium chloride into the sea to keep corals alive.

If you have good bed of crushed coral and/or live rocks and healthy water circulation there will be a natural entropic conversion of calcium carbonate in the substrate to Ca ions available in the water column for coral . It's the same process that a calcium reactor uses, just far more diffuse, but it's there. C02 / carbonic acid suspended in the water will dissolve calcium carbonate and provide it for corals ( or clog your plumbing and force you to buy a water softner). The bigger the tank the more reaction there is, and hence another reason bigger tanks tend to be better for SPS growth. The 'buffering capacity' of crushed coral isn't a marketing term. It's a chemical process that also provides Ca for corals, albeit in small amounts

I've seen proof of this first hand and witnessed very healthy SPS tanks where the tank owner does not dose or run a reactor and only does sporadic water changes maybe one or twice a year. These tanks also had deep crushed coral beds, and excellent water circulation and air turnover. They also werent small.

While yes this is true, a 45 gallon that is mildly stocked and with weekly water changes, isn’t going to deplete alk and Ca. I think the OP should be happy with this. If the OP’s tank was stuffed with SPS and various LPS with once monthly water changes, then I could see more of a need for concern.

 

[jtl]

I had a 100 gallon with lots of sps and lps and no softies. After 2 years my alk and ca remained constant with only water changes (IO regular salt) and a small amount of kalk in my ato container. Corals were growing at a moderate pace.

 

[Randy Holmes-Farley Verified Community Expert]

It is true that live rock and calcium carbonate sand can slowly dissolve and will need replacement in the long run. Some of that dissolution may be taken back up by corals, but it is usually a small contribution and dosing is most often needed.

 

[ReefersDelite]

Are you growing coralline?

Some. Not a lot

 

[BeejReef]

I guess I'd be a little perplexed if 18 months had passed and I hadn't seen alk/calc consumption. Are you seeing growth in any of your stony corals? Coraline?