Low Demand Dosing Question

[Travi]

Hi all!

So, I've got a new-ish system (~1yr) which is starting to get fairly stable now. I've fish and a mix of corals...mostly softies, zoas, leathers, GSPs, and have been slowly adding SPS but the SPS are all small frags, nothing bigger than 1" currently. All fish and corals appear to be super happy, zoas, GSPs are actively colonizing and polyps on the others are constantly out.

So I'm NOT LOOKING FOR THINGS TO CHANGE OR CHASE NUMBERS! lol Just putting that out there, but I am trying to make sure that I'm prepared to support a healthy tank by monitoring and adjusting proactively. I've read Randy's great articles on chemistry and followed and prepared his 3 part solutions. The only thing I've had to dose was some calcium to get it over 400 and some Mg to get it over 1200 (I've since read Mg testing can be fairly inaccurate). Also, before I knew better, I dosed some Marine Buffer trying to raise my pH which spiked my Alk to 11.7.

Tank is about 260g of total water volume, live rock and sand, running a skimmer, and some chaeto. Using RODI water with ATO and AWC doing about a 1% change each day. Feeding flake and mysis, no "coral food", and no other additives.

NO3 - 11ppm - 6ppm
PO4 - 0.13ppm - 0.02ppm (I accidentally bottomed out nitrates and phosphates so I had to dose a little of each but now both are relatively stable)
Calcium - stable around 430ppm
Alk - currently 9.6dKH but slowly dropping (new salt is measuring 8dKH so I'm assuming that's accounting for the slow drop)
Salinity - 35ppt
Mg - stable at 1280ppm

My assumption is that with the relatively low demand, that any calcium needs are being met by the replacement salt each day and that as the more calcium dependent frags start to (hopefully) grow, I'll be able to see calcium levels drop? Or am I expecting to see the increase in demand reflected in Alk levels dropping? I'm also assuming that until I need to start dosing 3 part, there's really no use in dosing the Part C?

Thanks in advance!

 

[Stevorino]

If you aren't already, I'd highly recommend just doing kalkwasser until your corals outpace what you can do.... and then switch to your 2/3 part

It's simple, really stable, and helps with ph

 

[Travi]

If you aren't already, I'd highly recommend just doing kalkwasser until your corals outpace what you can do.... and then switch to your 2/3 part

It's simple, really stable, and helps with ph

Forgive my ignorance, but what's the advantage of kalk over 2/3 part? Simplicity? My understanding is that we're basically accomplishing the same thing with both, right? Assuming you're using a 2 part that increases pH, of course.

 

[Stevorino]

Forgive my ignorance, but what's the advantage of kalk over 2/3 part? Simplicity? My understanding is that we're basically accomplishing the same thing with both, right? Assuming you're using a 2 part that increases pH, of course.

Yup, simplicity, which IMO is massively underrated in this hobby

It'll keep your alk and calcium balanced pretty well by default.... just dose to hit your alk target and the calcium will generally follow...... whereas if you do 2 part, there's a much higher chance that you at some point get them out of balance or over/under dose.

 

[Danny McElroy]

I use Tropic Marins All For Reef, and have great results with it as a single solution.

 

[Randy Holmes-Farley Verified Community Expert]

Hi all!

So, I've got a new-ish system (~1yr) which is starting to get fairly stable now. I've fish and a mix of corals...mostly softies, zoas, leathers, GSPs, and have been slowly adding SPS but the SPS are all small frags, nothing bigger than 1" currently. All fish and corals appear to be super happy, zoas, GSPs are actively colonizing and polyps on the others are constantly out.

So I'm NOT LOOKING FOR THINGS TO CHANGE OR CHASE NUMBERS! lol Just putting that out there, but I am trying to make sure that I'm prepared to support a healthy tank by monitoring and adjusting proactively. I've read Randy's great articles on chemistry and followed and prepared his 3 part solutions. The only thing I've had to dose was some calcium to get it over 400 and some Mg to get it over 1200 (I've since read Mg testing can be fairly inaccurate). Also, before I knew better, I dosed some Marine Buffer trying to raise my pH which spiked my Alk to 11.7.

Tank is about 260g of total water volume, live rock and sand, running a skimmer, and some chaeto. Using RODI water with ATO and AWC doing about a 1% change each day. Feeding flake and mysis, no "coral food", and no other additives.

NO3 - 11ppm - 6ppm
PO4 - 0.13ppm - 0.02ppm (I accidentally bottomed out nitrates and phosphates so I had to dose a little of each but now both are relatively stable)
Calcium - stable around 430ppm
Alk - currently 9.6dKH but slowly dropping (new salt is measuring 8dKH so I'm assuming that's accounting for the slow drop)
Salinity - 35ppt
Mg - stable at 1280ppm

My assumption is that with the relatively low demand, that any calcium needs are being met by the replacement salt each day and that as the more calcium dependent frags start to (hopefully) grow, I'll be able to see calcium levels drop? Or am I expecting to see the increase in demand reflected in Alk levels dropping? I'm also assuming that until I need to start dosing 3 part, there's really no use in dosing the Part C?

Thanks in advance!

Your assumptions are all basically correct. Alk and calcium will mostly fall together unless water changes mess with the demand ratio. In these early days, I’d wait until alk drops to the point that you want to raise it, then dose all three parts in proportion to it.

 

[Australian_Reef]

If you have a good supply of coraline algae don’t underestimate how much this can use up you kh/Ca/Mg. Your corals may not use much but the calciferous algae might. Keep testing. I’m dosing 2 part. The thing with kalkwasser I’ve wanted to try it … how long can I store it for once mixed?

 

[Travi]

If you have a good supply of coraline algae don’t underestimate how much this can use up you kh/Ca/Mg. Your corals may not use much but the calciferous algae might. Keep testing. I’m dosing 2 part. The thing with kalkwasser I’ve wanted to try it … how long can I store it for once mixed?

A tiny bit of coralline starting to grow, but not enough to deplete much yet, but that's one thing I'm watching as well.

 

[Travi]

Your assumptions are all basically correct. Alk and calcium will mostly fall together unless water changes mess with the demand ratio. In these early days, I’d wait until alk drops to the point that you want to raise it, then dose all three parts in proportion to it.

Thanks, Randy! Now I just need to figure out what I want my target Alk to be.