Question about Salt Mixes

[ReefPony]

It seems like everything I read says that the "ideal" alkalinity for a reef tank is 8-9. If that's the case, why is it that most of the "reef"/"coral" type salt mixes have a starting alkalinity of 11 or 12 dkh?

Looking at a few, Reef Crystals starting alkalinity is like 12. Red Seat Coral Pro is over 11.

[Tzwizzle]

Hmmm something is goofy. Reef crystals at 1.026 was a 7.7 alk for me. Having said that there's nothing wrong with running high alk but I suspect either your refractometer/hydrometer is off OR your test kit is out of whack. OR you got a hot batch of salt which is less likely but possible.

[ReefPony]

Hmmm something is goofy. Reef crystals at 1.026 was a 7.7 alk for me. Having said that there's nothing wrong with running high alk but I suspect either your refractometer/hydrometer is off OR your test kit is out of whack. OR you got a hot batch of salt which is less likely but possible.

That runs contrary to most of what I've read about the parameters of freshly mixed batches of Reef Crystals.

The general consensus of threads I've read about the topic suggest that the "typical" starting alkalinity of a batch of Reef Crystals is around 12.2 dkh with some people measuring alkalinity as high as 13.

On their web site, Red Sea even shows that the starting alkalinity of their Coral Pro line of salt is over 12 dkh (to compare, they show the starting alkalinity of their regular Red Sea Salt as 7.8-8.2).

[Tzwizzle]

What are your Cal/mag numbers?

I'm using a Salifert Alk test kit which comes with a 6.7 dKH check standard. Hit it dead on so I know my kit is good.

My calcium for Reef crystals was 450 Calcium and magnesium was 1320. Both of which line up to the proposed numbers on the bucket. :confused:

However, I do think coral pro salt does run on the high end of things but I'm not sure about those Reef Crystal number based off what I've seen.

[ReefPony]

Reef Crystals discussion aside, I still wonder why those higher alkalinity numbers are targeted by some of the higher end reef salt makers when the conventional wisdom is to keep alkalinity somewhere between 8-9 dkh. It definitely seems like some of the makers go with higher levels (Red Sea Coral Pro) and others try to just give a baseline level (regular Red Sea Salt, for example).

I guess that, in a tank that's pretty heavily stocked with growing SPS and LPS, the rate of calcium and carbonate usage in the tank could make elevated initial levels beneficial and reduce or eliminate the need for dosing something like 2 part.

[Tzwizzle]

That is correct. Tanks with mature SPS often consume 2 dKH a day. So you'll want that higher alk salt unless you are dosing everyday. The high alk salt makes it so you don't have to dose as often. 8 is ideal but 7-12 is ok. The way I look at it you can either pay for your buffer in your salt mix or add your buffer in manually. Which one is better depends on how often you water change, which salt brand you use and what you are keeping. If you are keeping soft corals and mushrooms the elevated alk level in some of the premium salt is wasteful. You'd be better off with a cheap salt and occasionally add your 2 part.

[Kobashi]

Speaking with advanced aquarists and some personal experience… (I've been in the hobby since 1995, though my avatar for here is newer). My corals are more colorful when I can sustain higher dKH.

Some good aquarists have encouraged me to have 9-12dKH, but some of them have gone up to the teens themselves. Speaking from my own experience, I can easily maintain around an 8 with good water changes. To consistently get around a 9+ (consistently), I have to dose, (and because I asked, to get a 11+, you really need some automation (with an aqua controller of some type) to automatically dose accordingly to low and high points in the day or run a reactor.

That said, the most noticeable difference I can see is in SPS. At 9+, the brownish corals with a light sheen of color, start to have more of a (often iridescent) sheen. Typically, this is more like what I saw in the LFS and why I bought it, but was a little surprised after a couple of weeks when it seemed to lose some of the "wow" factor (but doesn't look bad). My acans "seem" to color up just a little more, but I can't 100% prove that one... (the SPS difference is noticeable for sure).

Of course, with light daily dosing (2x per day separating alk and CA by about 10 hrs) more buffer and CA (and some mag… but that seems to be quite steady in my tank) and consistently raising to around 10dKH, changes take about 10 days to notice. That is to say, it is NOT instantaneous gratification. SPS and LPS do seem to grow faster.

All this said, I honestly can say I do get busier months than others. When I "fall behind" on my dosing, I typically do a little water change and stop dosing all together… things seem to hover around 8 after a few weeks. Corals are perfectly fine.

All salts are not the same. That said, salts like Instant O are great for FO tanks, but the reef tanks need elevated (and trace) elements. I use Red Sea Coral Pro salt, (but I once bought another "pro"… I didn't see any difference).

[santanzchild]

My tank maintains its self at 6.8dKH using IO Reef Crystals. I have Ca and Ak for dosing but with no coral have no need to. So the number I am getting off my Hanna and Red Sea kits are what IO is mixing at.

[Randy Holmes-Farley]

In a thriving reef tank of hard corals, the added alkalinity from a water change is small potatoes relative to what you need to add each day. Many folks add 1-3 dKH per day, while a 10% water change in a reef tank at 8 dKH with 12 dKH water only moves the alk to 8.4 dKH. :)

The only people that need to think about keeping a low alk are folks who have SPS in a very low nutrient system where alk levels need to be closer the NSW levels of about 7 dKH than most tanks, which are usually fine in the 7-11 dKH range.

[ViktorVaughn]

Exactly what Randy said. I was nervous about the high dKH of reef crystals as well (always between 11-12 dkh when I test my 1.026 batches) but after figuring out how much my tanks alkalinity would raise after a 10 gallon water change on a 52 gallon system I was fine with the high dKH numbers of reef crystals. My tank consumes right around 2 dkh of alkalinity a day and a 20% water change would only give me about 1/3 of a daily dose of alkalinity. I keep my alk at 8.4 dkh so a water change only bumps my alkalinity up to 9.1 or so (42 gallons x 8.4 dkh + 10 gallons x 12 dkh=472.8/52 gallons= 9.09 dkh post WC)