Low Alkalinity question...

[falcooo]

I’ve got a 10 gallon mixed reef, and as of the past few weeks I’ve been noticing that my alkalinity has been hovering steadily around 5 dKh. Calcium is steady ~420 and Mg around 1450. I change 2 gallons of water with Reef Crystals salt every 4 days. 

 

I previously thought that if one of Ca or Alk was high, the other would be low, and vice versa. However in my case, calcium and magnesium are both steadily where I want them. But alkalinity is now very low. Granted there hasn’t been drastic fluctuations, as this has been the case the past few weeks and my water changes have been routine.

 

Help me understand this, and given these #s, should I be dosing alkalinity by itself regularly to get back to where I want it. Obviously WC aren’t keeping up anymore.

[Garf]

I am kind of in the same boat, so I will follow.

 

I do know that Alk is at a lower percentage than calcium, that is why people tend to test mainly alk, as fluctuations will show up more testing that parameter. I cant remember what the ratio was, but it is possible that with the accuracy of tests and the testing method a drop of 30-40 in calcium could equate to almost 2dkh. Though 5 dKh seems really low. What does your PH test at?

 

I missed a few days of dosing (manual atm), as have within the last couple weeks started to dose. My last WC yesterday, I tested at 6.6 alk. After WC, 7.1 dKh and 420 Ca. My mix typically test at 8.4 and 430. Not too concerned with the alk numbers, but I am trying to dial in the amount of Tropic Marin one part All for Reef I need to dose. 

[A.m.P]

"" High Calcium, Low Alkalinity
     This problem tends to be pretty common. Especially in newer or lower coral load tanks.

     Alkalinity is consumed at a greater rate in any reef compared to calcium. This is due to the fact that alkalinity is consumed by not just corals, but also by nitrogen creating bacteria that process the wastes inside of your tank.

     Not to mention some corals, while acclimating to your system, do not consume calcium. Your calcium consumption will not change until the coral begins to grow and consume. 

     Because of this you will need to use a soda ash solution such as Reef Pro Alkalinity to raise your alkalinity to the desired level and stop dosing calcium and raise your alkalinity dose.

     Do this until calcium begins to be consumed and lowers to the desired range. Once the calcium is in the desired range resume regular dosing.""

http://reefprostore.com/Aquarium-Chemistry.html

Detailed bits: (Advanced aquarist has a really in-depth guide of relationships and causes, but their website is pretty consistently down lately)
http://reefkeeping.com/issues/2007-04/rhf/index.php

[Garf]

Fun stuff. Tested dKh below 6 today. This is with dosing Tropic Marin All For Reef. Probably dosing way too little, was trying 1ml every day, based on a guess at consumption a few weeks ago. I do hear that this additive may take a couple days to give a valid reading of dKh, so I will see what tomorrow brings.  Upping it to 2ml a day, see what that does. Also looking at my journal, my water change two days ago I tested 1200 mag, that needs to come up also. Corals look happy though, but I have noticed my plate coral doesn't look to be extending as much as it did when I got it a bit over a week ago.

[billygoat]

I have some experience with this as well. My tank consistently consumes about 12ml of KH solution (BRS liquid sodium bicarbonate) every day, but I only dose calcium about twice a week. I believe this is because my system has few corals but a very robust community of microbes and algae; as @Amphrites mentioned there are various other organisms that consume bicarbonate but aren't necessarily interested in calcium.

 

As far as I can tell this is nothing to worry about. I'd say you should gradually bring your KH up into a desired range (I aim for anywhere between 8.0 - 9.0 dKH) and then dose enough to keep it there, and everything should be fine. Fluctuations in KH are generally more stressful for livestock than fluctuations in Ca or Mg, so it's worth paying more attention to alkalinity than to the other core parameters, at least in my opinion.

[SaltyGallon]

I was in the same boat as you - currently running a 10g mixed reef with just a weekly water change, and before I knew it my alk was at 5 something before WC day - not cool! Everything was fine and dandy at first but when the corals settled in and started happily growing they were stripping the alk and ca quicker than I could supplement it with the old weekly water change. From what I understand this is a classic problem with people who run mixed nano tanks on WC's only - they're fine for a while but then they reach this point where the WC can't keep up with the alk and ca demands and they drop lower and lower, potentially to as low a level as the size of the WC you're doing, all because the WC can't keep up over time. What's nuts is people start losing heads on LPS colonies etc. in established tanks and still don't test their alk! A guy I buy corals off was telling me about a friend who ran his tank like this for ages and tested the alk and found it at 4 something, and concluded it had probably been there for a while, but everything was fine because the levels slowly trickled down to that point, rather than swung down there.

 

But anyway, easy to correct with dosing. Do a WC and measure your alk/ca/mg levels after, and then leave it a few days before testing again - you can then work out your average daily consumption and go from there. Depending on the level you want to get it up to you can then manually overdose for a little while to bump it up to desired levels over the course of a few days. I've been manually dosing daily/every other day with the Seachem Reef Fusion two part (ca and alk only, as my mag is steady enough with the old weekly 20% WC) and have had no problems keeping nice steady params, with alk around 8 and ca around 400-420. 

 

All tanks are different but for what it's worth I dose 1.1ml of the alk solution and 0.5ml of the ca solution, daily, and that keeps everything steady eddy. I was expecting to have to dose more calcium but as touched on by someone else above my ca consumption isn't, in practice, as much as my alk.

 

 

[DSFIRSTSLTWATER]

5 hours ago, Azur said:

I was in the same boat as you - currently running a 10g mixed reef with just a weekly water change, and before I knew it my alk was at 5 something before WC day - not cool! Everything was fine and dandy at first but when the corals settled in and started happily growing they were stripping the alk and ca quicker than I could supplement it with the old weekly water change. From what I understand this is a classic problem with people who run mixed nano tanks on WC's only - they're fine for a while but then they reach this point where the WC can't keep up with the alk and ca demands and they drop lower and lower, potentially to as low a level as the size of the WC you're doing, all because the WC can't keep up over time. What's nuts is people start losing heads on LPS colonies etc. in established tanks and still don't test their alk! A guy I buy corals off was telling me about a friend who ran his tank like this for ages and tested the alk and found it at 4 something, and concluded it had probably been there for a while, but everything was fine because the levels slowly trickled down to that point, rather than swung down there.

 

But anyway, easy to correct with dosing. Do a WC and measure your alk/ca/mg levels after, and then leave it a few days before testing again - you can then work out your average daily consumption and go from there. Depending on the level you want to get it up to you can then manually overdose for a little while to bump it up to desired levels over the course of a few days. I've been manually dosing daily/every other day with the Seachem Reef Fusion two part (ca and alk only, as my mag is steady enough with the old weekly 20% WC) and have had no problems keeping nice steady params, with alk around 8 and ca around 400-420. 

 

All tanks are different but for what it's worth I dose 1.1ml of the alk solution and 0.5ml of the ca solution, daily, and that keeps everything steady eddy. I was expecting to have to dose more calcium but as touched on by someone else above my ca consumption isn't, in practice, as much as my alk.

 

 

I use the reef fusion as well. My tank uses .1-.2 dkh a day so I dose .8ml every day to keep around 8.5-8.8. My tank is weird because some days it'll move .2 and other days it doesn't move at all

[mcarroll]

On 8/26/2019 at 8:00 PM, falcooo said:

I previously thought that if one of Ca or Alk was high, the other would be low, and vice versa. However in my case, calcium and magnesium are both steadily where I want them. But alkalinity is now very low. Granted there hasn’t been drastic fluctuations, as this has been the case the past few weeks and my water changes have been routine.

 

Help me understand this, and given these #s, should I be dosing alkalinity by itself regularly to get back to where I want it. Obviously WC aren’t keeping up anymore.

I know this is a stale thread -- hoping you'll update! 😎

 

It's basic addition/subtraction at the end of the day.

 

There's only 200 ppm of alkalinity, where there are 420 ppm of Calcium and almost 1400 ppm of magnesium.

 

they get used up more evenly than they are concentrated in the water, so alk can theoretically go all the way to zero by combining with calcium/magnesium, and not even ruin the levels for either one.

 

Dosing alkalinity is THE MOST important of all three in a stony coral tank for this reason.