Why is lower alkalinity preferred?

[adobo]

As a new reefer (just have my first quarantine tank set up), I appreciate everyone's input on this thread. My 10 g tank has been running a month, has some zoas, a finger leather, xenia and some green star polyps, clownfish, some ricordeas and CUC. Weekly 10% water changes. All seem to be doing great except the zoas aren't very happy. Most of what I've read says to target alkalinity to 9 (and recently I ordered corraline algae and their instructions say to keep alkalinity at 8). My IO crystals mix to dKh of 11 and when I test I'm getting around 10.5, which is certainly higher than what I want in this simple little tank. At the same time, my pH has been low (7.8 or even lower), which made NO sense to me with high alkalinity, unless I'm just not aerating the tank enough and it's carbon dioxide building up. So I'm doing more aeration to try to raise pH and have no idea how to lower my dKh (still learning), plus the tank is SO new that I don't yet know what it's "normal" levels will be. I'd love to be able to use a salt mix which starts me at 9 dKH and then be able to supplement calcium and alkalinity and/or magnesium as needed. For me this QT is like a rehearsal for my 90 gallon which is on order.

I watched the BRS instructional video on calcium, carbonate and magnesium and it was excellent. I get that calcium and carbonate like to bind together but when they do they become unavailable to corals, so we'd rather have them floating around loose in the water column. Magnesium is what keeps them from hooking together. My little tank's magnesium is a little low and what worries me is that if I add a little, it will make more carbonate be free (unbound) which will raise my alkalinity, and I want to LOWER it. But on the other hand I don't like having low magnesium. It's so true that everything relates to everything else!

And yes, I know my tank is so new I probably should just leave it alone and see what it settles out to be. It just bugs me that every time I do a water change I'm adding in my high alkalinity IO salt mix and I lose hope of getting to 8 or 9 dKh. Didn't know where to look for other options. This discussion is really informative, thanks from a newbie!

Regarding your low pH, let me offer my observations on my tank. We have three people in my house pretty much all day (coronavirus and what not). If I don't open the windows, by morning, my tank's pH will read somewhere around 7.80. It will pretty much stay there all day if I don't intervene. If I open the window in the room and pull in some "fresh" air, the pH will eventually get above 8.00. I had it at 8.10+ over the weekend.

In reading in R2R, conventional wisdom seems to be that the CO2 expelled by the other inhabitants of the home (humans, dogs, cats, etc) are causing the low pH. Apparently there is enough CO2 in the air that the CO2 winds up in the tank via gas exchange. By pulling in "fresh" air, I seem to be able to rid the room of excess CO2. I'm sure this has been studied using real science but just observing what happens when I bring in fresh air, the explanation seems entirely plausible.

 

[Mountain Reefer]

I've been pondering this question also and was thinking of starting a thread when I ran across yours (good timing, eh?).

After reading the responses, I haven't seen one that resembles a convincing argument as to why "lower" alkalinity is preferred. In the first place, I think there should be a clear definition of what is meant by lower.

In my case, I am considering two salt options - Tropic Marin pro and Tropic Marin classic. What's the difference between the two? Let's look at the manufacturer's specs.

• Classic: approx. 9-10° KH, calcium approx. 380 ppm, magnesium approx. 1260 ppm
• Pro: approx. 7° KH, calcium approx. 440 ppm, magnesium approx. 1350 ppm

The conventional wisdom seems to be that the pro variety is preferred for reef tanks. That's what the BRS guys push and seems to be what many of the Tropic Marin users are using (based on a poll I saw here on R2R recently). Looking at the manufacturer's specs, we can see that the pro variety has more calcium and magnesium yet is lower in alkalinity.

If memory serves, it is difficult to produce a salt that is high in alkalinity as well as calcium and magnesium. Its like a seasaw between alkalinity and calcium as to the maximum amount you can keep in solution. If you try to elevate either or both too much, you get precipitation. Maybe someone who knows a lick about chemistry can keep me honest on this and perhaps elaborate.

If you keep stony corals, you are always concerned about calcium and mindful about magnesium. For these reasons, a salt that has "elevated" calcium and magnesium would seem superior. With that said, you still need to keep an eye out for alkalinity.

This is the "theory" as I understand it. Now, let's talk about "in real life". BRS ran some tests on salts. The numbers they showed is that Tropic Marin pro mixed with around 420ppm calcium and 7dkh. Tropic Marin classic mixed with around 410ppm calcium and 8-9 dkh. I'm working off of memory so I might be off a tad. Based on the real life numbers that BRS shared, I have no flipping idea why Tropic Marin pro is supposedly better. Is it because of 10ppm difference in calcium? I posed this same question to someone at BRS. The answer was every bit as unconvincing as the ones you have gotten on your thread.

So back to where I started - I have the exact same question as you - why is a salt with lower dkh supposedly better than one that has higher dkh? To phrase the question more precisely, let me add, "assuming all else is relatively equal."

The others posting on this thread about how you need to use salt that is close to what your target parameters are ... they are right but they are answering an entirely different question altogether.

One last bit - all this "keep your alkalinity low" business seems strange to me. Tropic Marin pro is a "johnny come lately" salt. Hobbyists have been using Tropic Marin classic with its "elevated" alkalinity for decades to keep the most beautiful reef tanks.

My understanding is the lower alkalinity with higher calcium and magnesium In the TM pro is to prevent precipitation in storage containers after mixing

 

[fcmatt]

I want my water to be similar to the ocean. That is why I run lower. Simple as that.

 

[BrightReef]

Each tank is different when it comes to a preferred Alk. Keep an eye on where it's at and make small adjustments. Mine is happiest in the mid-high eights.

 

[Beonedge]

If you keep alk lower (8.0) and add sps from system with higher alk than yours, it will stress corals (increased survival rate) less than if your alk is high and coras coming from system with low alk

 

[mkwarner77]

I've just started using kalkwasser to maintain calcium levels. I used to use Bi-ionic 2 part dose. I'm finding that kalk seems to raise kh and ph to pretty high levels. That may be the reason to look for low alk salt mixes, to keep from dosing 1 more thing to bring the other levels down.

 

[ReefPig]

I use TM Pro, as in my opinion, it’s the best representation of NSW and mixes clean/quickly.

I mix 50L to 35PSU, then add 10ml of Triton CO3 Alkalinity buffer, which lands me at my target of around 8dKH.

I replenish my tank with Triton Core7 using GHL doser. My params have been spot on for a while now. Regular ICP’s are showing my elements are also looking good.

I decided on 8dKH, as it gives me a little wiggle room up and down.

I water change every two weeks, despite using Triton, as I follow the Triton “other methods” dosing.

PH is far more important to accelerating coral growth than pushing up alk.

 

[ReefPig]

My understanding is the lower alkalinity with higher calcium and magnesium In the TM pro is to prevent precipitation in storage containers after mixing

No, it’s because that’s NSW levels. It doesn’t have high Ca, Mg, they are correctly aligned. (440 and 1370).

 

[Randy Holmes-Farley Verified Community Expert]

Its also worth noting that many people measure alkalinity with an improper endpoint, which causes them to over estimate alkalinity.

What is the basis of this claim?

 

[EMeyer]

If you keep alk lower (8.0) and add sps from system with higher alk than yours, it will stress corals (increased survival rate) less than if your alk is high and coras coming from system with low alk

Edit: I have misinterpreted your post. Not enough coffee. I agree completely

 

[EMeyer]

What is the basis of this claim?

I can't recall who made the thread but its been discussed a lot. Was it Jim Welsh? As I recall, he measured pH of endpoints and compared it to colors, showing that the pinkish purple color many users were shooting for as the endpoint as actually past the pH based endpoint, causing an overestimate in alkalinity. Have I remembered some of that wrong?

I guess I don't have data on how many users were overshooting the endpoint, I just know a lot of people in that thread said they were overshooting. I know I used to, until I adjusted my definition of what constituted the endpoint.

I think you've discussed pH-meter based based titration of alkalinity - whats your practice? Titration with a meter or color change?

 

[92Miata]

One salt I’ve looked at was the tropic Marin pro which is very popular but it only as an alkalinity of 7, why so low?

Because the ocean is that low. And TM is assuming that someone who is running a reef tank is supplementing alk and ca.


Typically reef tanks are run between 7-9 dkh (there are people higher, but the majority fall in that range). Salt on the other hand runs from about 7 to about 14. Salt with super high alk means either you need to be really careful about water changes, or you need to alter the salt.

 

[MabuyaQ]

All depends on your husbandry, setup, animals and intended use of the water. Do a 10% daily waterchanges to keep levels up and compensate for consumption is not a problem for a small aquarium. That 10% 11dKH waterchange just raised your 8dKH water to 8.3dKH, not really a problem for many species as the dKH consumption in small aquarium can easily be 0.3 dKH.
Have a big aquarium kept at 10+ dKH, you don't want to waste that alkalinity by doing waterchanges with 7-8 dKH salt used for waterchanges.
Also there is nothing wrong with using more than one type of salt and mix up a batch with high and low dKH salts together at appropriate ratios.
I haven't done a real waterchange in 8 years but still have two different salts stored away in case it is needed. When I used to do regular 10% waterchanges I also used two different salts.

 

[ScottB]

"Why is lower alkalinity preferred?"

My personal answer: because all of my favorite acropora vendors run 7.5 to 8.5. You might be surprised to discover how many vendors run in this range. I only buy from folks that run this range in the USA.

Europe, Middle East and Asia often run much higher dkh levels. May have something to do with the relative popularity of Red Sea method, not sure.

 

[ReefPig]

"Why is lower alkalinity preferred?"

My personal answer: because all of my favorite acropora vendors run 7.5 to 8.5. You might be surprised to discover how many vendors run in this range. I only buy from folks that run this range in the USA.

Europe, Middle East and Asia often run much higher dkh levels. May have something to do with the relative popularity of Red Sea method, not sure.

I'm from the UK, we have european forums too which I use a lot, I don't know many people pushing high dKH, actually I don't know many using the RedSea method (can't think of any). A lot of people run Triton, Ca Reactors, or just DIY 2-part, a few run ATI.
7.5 - 9 is the general rule here too.

I consider high being anything over 10.

 

[Reef.]

I've been pondering this question also and was thinking of starting a thread when I ran across yours (good timing, eh?).

After reading the responses, I haven't seen one that resembles a convincing argument as to why "lower" alkalinity is preferred. In the first place, I think there should be a clear definition of what is meant by lower.

In my case, I am considering two salt options - Tropic Marin pro and Tropic Marin classic. What's the difference between the two? Let's look at the manufacturer's specs.

• Classic: approx. 9-10° KH, calcium approx. 380 ppm, magnesium approx. 1260 ppm
• Pro: approx. 7° KH, calcium approx. 440 ppm, magnesium approx. 1350 ppm

The conventional wisdom seems to be that the pro variety is preferred for reef tanks. That's what the BRS guys push and seems to be what many of the Tropic Marin users are using (based on a poll I saw here on R2R recently). Looking at the manufacturer's specs, we can see that the pro variety has more calcium and magnesium yet is lower in alkalinity.

If memory serves, it is difficult to produce a salt that is high in alkalinity as well as calcium and magnesium. Its like a seasaw between alkalinity and calcium as to the maximum amount you can keep in solution. If you try to elevate either or both too much, you get precipitation. Maybe someone who knows a lick about chemistry can keep me honest on this and perhaps elaborate.

If you keep stony corals, you are always concerned about calcium and mindful about magnesium. For these reasons, a salt that has "elevated" calcium and magnesium would seem superior. With that said, you still need to keep an eye out for alkalinity.

This is the "theory" as I understand it. Now, let's talk about "in real life". BRS ran some tests on salts. The numbers they showed is that Tropic Marin pro mixed with around 420ppm calcium and 7dkh. Tropic Marin classic mixed with around 410ppm calcium and 8-9 dkh. I'm working off of memory so I might be off a tad. Based on the real life numbers that BRS shared, I have no flipping idea why Tropic Marin pro is supposedly better. Is it because of 10ppm difference in calcium? I posed this same question to someone at BRS. The answer was every bit as unconvincing as the ones you have gotten on your thread.

So back to where I started - I have the exact same question as you - why is a salt with lower dkh supposedly better than one that has higher dkh? To phrase the question more precisely, let me add, "assuming all else is relatively equal."

The others posting on this thread about how you need to use salt that is close to what your target parameters are ... they are right but they are answering an entirely different question altogether.

One last bit - all this "keep your alkalinity low" business seems strange to me. Tropic Marin pro is a "johnny come lately" salt. Hobbyists have been using Tropic Marin classic with its "elevated" alkalinity for decades to keep the most beautiful reef tanks.

Wow great post, I think you can read minds as your summary is perfect, I have to admit I’m still not totally there yet with this alkalinity question.
Being told to pick a salt that matches your tank alk doesn’t really help as I’m trying to pick a new salt with very little understanding of the best lvl to go for.

I’ve decided to go for Tm pro (7dkh), my tank is a nano 14g LPS tank, anyone that would like to agree with this choice or disagree and think the classic at 9dkh would be a better option please step in.

 

[ScottB]

Wow great post, I think you can read minds as your summary is perfect, I have to admit I’m still not totally there yet with this alkalinity question.
Being told to pick a salt that matches your tank alk doesn’t really help as I’m trying to pick a new salt with very little understanding of the best lvl to go for.

I’ve decided to go for Tm pro (7dkh), my tank is a nano 14g LPS tank, anyone that would like to agree with this choice or disagree and think the classic at 9dkh would be a better option please step in.

I don't use it, but you cannot go wrong with TM Pro.

(I use IORC because it is cheaper and I mix 160 gallons a month so...)

 

[adobo]

For reference, this is what BRS posted regarding alkalinity levels for some salts they tested. Note that Tropic Marin classic has been around at least 25 years (though I don't know if they have changed their formula). IO has been around just as long if not longer. RC has been around a long time too.



Hobbyists have been keeping the most demanding wild collected SPS with all three salts for at least that long (with varying degrees of success, of course). I see that there have been much new knowledge gained in the past 20 years and many innovations and improvements with reef keeping equipment. These days, it is not uncommon for hobbyists to keep SPS in nano tanks - something that was virtually unheard of 20 years ago. My guess is that the better success rate for hobbyists has more to do with the better availability and higher quality of knowledge now plus better equipment and less to do with the new salts with supposed "natural" levels of alkalinity.

 

[ReefPig]

My guess is that the better success rate for hobbyists has more to do with the better availability and higher quality of knowledge now plus better equipment and less to do with the new salts with supposed "natural" levels of alkalinity.

Something about your comment above really annoys me.
Is this conversation about the success rate of keeping corals and using certain salts?

The OP is asking about why people run tanks at a lower alk than other people, why is lower preferred.

Consistently, we said it's because those levels are closer to NSW.

Tropic Marin has been making salt a very, very, long time. TP pro is nothing new and it mixes to close to NSW level, at least what we're capable of testing.

"with supposed 'natural' levels of alkalinity", what does this even mean? Go to the sea and test it, it costs you nothing.

Your comment comes across bitter, like we're playing an elitist game of "my salt is better than yours" and you're bitter about it.

TP Pro mixes to NSW level, point blank period
It also mixes far better and cleaner than other salts I've used.

Use it, don't use it, nobody cares.
We simply answered his question.

 

[ReefPig]

Wow great post, I think you can read minds as your summary is perfect, I have to admit I’m still not totally there yet with this alkalinity question.
Being told to pick a salt that matches your tank alk doesn’t really help as I’m trying to pick a new salt with very little understanding of the best lvl to go for.

I’ve decided to go for Tm pro (7dkh), my tank is a nano 14g LPS tank, anyone that would like to agree with this choice or disagree and think the classic at 9dkh would be a better option please step in.

Ignore the naysayers.
TP Pro is the benchmark IMO. TP Classic is also very good. Red Sea Blue Bucket is also very good.
I would never use RS Coral Pro though, far too high alk, doesn't suit me.