View Full Version : What alkalinity level do you keep in your REEF?

04-30-2010, 05:17 PM
Please do not vote if your tank is not a reef.


I have found it very interesting to watch "the" reef tanks of the time over the years. Something I have noticed is 10 years ago, even up to 3 years ago Salifert test kits were "industry standard" for most of the leading reef keepers, they still are for many people. During this time, the leading reef keepers have found that keeping an alkalinity level of 9-10 dKH has given them the best results.

In the last 3 or so years Elos kits have begun to move in as the NEW (oh la la lol) "industry standard" for many leading reef keepers. People are also starting use devices like colorimeters, and more accurate test kits like Hanna, LaMotte, Hach. Many of today's leading reef keepers are beginning to suggest (and keep) lower alkalinity levels of 7-8 dKH which makes a lot of sense since NSW is close to 7 dKH.

Interestingly enough, many people are noticing that these more accurate means of testing are often reading 2 dKH lower than a Salifert test kit. I have both Salifert and Elos alkalinity test kits (both new), and I have also compared them to a Hanna Colorimeter. When I tested the same sample of my tank's water I got:

Hanna Colormeter = 7 dKH (converted from 125 mg/l)
Elos = ~7 dKH (Elos goes up in 1 dKH increments, it was pretty close to 7, as it barely changed)
Salifert = 9.15 dKH

Anyway, this is all just something that I have noticed over the years be reading tank logs, journal type books (old and new), etc. Recently, I have also heard other people talking about this. By no means is this some sort of published data. :lol: Well maybe, but I don't know where it would be.


So long story short, I am interested to see some more evidence. So, what test kit do you use, and what level do you keep your alkalinity at?

If you have two kits, and have tested the same sample of water with both, you can vote twice. :D I forgot to. *smacks forehead*

04-30-2010, 05:24 PM
8 dkH with API test kit.

04-30-2010, 05:27 PM
Thanks Kien, I actually quite like the API alkalinity test kit, it is reliable for giving consistent results, but for this particular poll I'm really more interested in Salifert VS Elos, that's why I put the API into the lower end category. :redface:

04-30-2010, 05:59 PM
Elos 8-9 for us.

04-30-2010, 06:52 PM
8 dkH with API test kit.

+1, although the API test kits are a little cheaper (around $45.00 for the reef master kit) I still find them very reliable. I haven't used many different Alk test kits but any kit relying on distinct color changes over the old Hagen "Pink nitrate test" comparison is better in my books.

danny zubot
04-30-2010, 07:42 PM
I have used Salifert, Elos and API for Kh tests and find that I got similar readings with all three. Since I don't really care to know to the tenth of a degree what my KH is, I've opted to use API lately for it's simplicity. I try to keep my KH at around 9-10 Kh via my API test. It's good to know that I don't need to keep it that high though.

04-30-2010, 09:11 PM
Thanks for the info Danny.

04-30-2010, 11:34 PM
I aim for around 7-9, I like to keep it closer to 9 but the tank likes to be around 7 it seems.

I too bought the elos kit after people were complaining about the salifert. I got pretty much the same readings for both elos and salifert. And the elos kit had incorrect instructions which I wasn't impressed with so I've stuck with salifert.

05-01-2010, 12:19 AM
I voted 8 to 9 dkh with both Salifert & Elos. No particular preference. All through the '90,s and into 2000, I always used the cheaper FastTest or whatever the name was. Measured the same as the Salifert I used. Could buy the kits for $10 but dont see the anymore.

I like API for phosphate and nitrate, so may switch to them, as I see you guys say they make alk. test kits also.

05-01-2010, 12:29 AM
with my elos i get a reading of 6
with the API i get 8
too big of a difference??\
anyone else see different results?

05-01-2010, 03:43 AM
I have lost faith in Salifert alkalinity test kits. They really seem to vary. The one I have now reads 2 dKH lower than the Elos and the Hanna Colorimeter, and the Salifert alk kit I had before that read 3 dKH lower. That's pretty frustrating.

Thanks for voting everyone! Lots of interesting information here...everyone is all over the charts!

05-01-2010, 03:55 AM
I've used both salifert and elos. I never noticed noticed a big difference between the 2 and prefer to use salifert but it isn't always easy to get

05-01-2010, 03:59 AM
i have never used salfert. except for \mg and it seems to be a pain to use IMO compared to elos or API
dont know about the other tests like Ca.
how easy is it to test ca or k with salfert vs elos

05-01-2010, 07:25 AM
Just so I know where to vote, where do you rate the seachem test as for high end, low end? Thanks.

05-02-2010, 01:26 AM
Seachem is low end. Thanks for voting!

i have never used salfert. except for \mg and it seems to be a pain to use IMO compared to elos or API
dont know about the other tests like Ca.
how easy is it to test ca or k with salfert vs elos

Elos kits are done in the same fashion as API kits.

Salifert's calcium, alkalinity, and magnesium are all very similar tests. Salifert's alkalinity is a bit tricky because the color changes slowly over several drops from blue, to blue purple, to purple, to purple pink, to pink. According to customer service you're supposed to read it when the color is purple pink. This can be difficult to tell, but in all reality the difference is like 0.25 dKH all the way from blue to pink so who cares to be that picky?

I wish Elos was as picky as the Salifert kits though, as with Elos (and API) you go up by quite a jump. I guess you get used to it. I just know that I don't want the color to change when I put in 7 drops (7 dKH), but I do want it to change when I put in 8 drops (8 dKH) because I want alkalinity between 7 and 8. Takes a bit of getting used to not knowing exactly what you're at when you're used to kits like Salifert.

05-02-2010, 01:32 AM
low end for 35$. I would hate to see how much the high end kits are worth!

05-02-2010, 01:40 AM
That is simply because I am more interested in Salifert VS Elos than anything, and you can't put the Seachem kits with kit like Hanna, LaMotte etc which are very pricey. Some of API and Seachem's kits are comparable (imo) to Salifert which I would consider mid-end test kits, but that is irrelevant for the purpose of this poll. Imo, Elos is a slight step up from Salifert, but neither Salifert nor Elos could be considered high end kits.

IMO high end would be: LaMotte, Hanna, Merck, etc. Mid would be: Elos, Salifert, Seachem, API, etc. Low-end would be: Hagen, Instant Ocean, etc.

API kits are good bang for the buck.

05-02-2010, 02:55 AM
My tank was just started up but my new water change water tested the same as the tank (Elos 10 dKH with Reef Crystals).

You can't bring it down can you? I doubt it will be an issue once there is a demand for it but right now is there a problem with that?

05-02-2010, 05:36 AM
Elos test kit - Alk - 16 drops 8 dkh - where I try to keep it

05-02-2010, 05:09 PM
I lost quite a few sps colonies and frags because of a bad Salifert Alk test kit( read higher than the alk actually was) so i switched to API. From what i have read everywhere, not one test kit is always accurate. Some people have had bad Salifert, Elos or API test kits. So i tought i might as well save a few bucks with API. Oh and after that i got a bad Salifert test kit too :(
This is sooo frustrating.
I keep my alk at around 8 because i'm dosing VSV.

05-02-2010, 05:19 PM
My tank was just started up but my new water change water tested the same as the tank (Elos 10 dKH with Reef Crystals).

You can't bring it down can you? I doubt it will be an issue once there is a demand for it but right now is there a problem with that?

No, you can't bring it down. It will probably be better once you have a demand for it. This is one of the reasons I switched away from IO which is 11 dKH out of the bucket. When I'm trying to keep 7-8 dKH a water change with 11 dKH can make quite a shift. I switched to H2Ocean and am happier that the alk is about 8.75 dKH (Elos) out of the bucket (first bucket I have tested...haven't double checked my numbers yet). I'm stoked I don't have to dose calcium, alkalinity, or magnesium with the H2Ocean, but the potassium is just as low as IO at ~250 ppm.

Son Of Skyline
05-03-2010, 11:33 PM
I have 2 relatively new Elos KH test kits (correct instructions) that give me different readings. Both are supposed to be identical kits but one will read 8.5 while the other will read 7-7.5. It appears that the reagent is the same in both kits but the droppers are clearly different and one produces visibly larger drops, thus needing fewer drops to change colour and giving me a lower reading.

I don't know which one is accurate since I don't feel like going out and buying a third kh test kit so i've just been testing twice and splitting the difference.

Anybody else ever have Elos inconsistencies?