dKH problems

[rfdoc]

A few months ago I noticed the coralline algae on the back wall of my tank started to disappear. I replaced my API test kits with Salifert kits based on recommendations from here. I discovered my dKH was 14, so I stopped dripping kalk in my topoff. My magnesium was also a little low so I purchased a Tech M additive to raise it slowly over a week. This brought my mg from 1125 to 1290 and my dKH dropped to 11. Calcium was 420. Then I did roughly 15% water change and ran tests again - my dKH was back to 14! So tonight I tested a new batch of fresh saltwater using reef crystals. Two separate buckets did not even register using the salifert test kit, meaning the reading was over 16! I then used the dKH "check" solution that came with the kit, it says it should read 7.8 but my tests show it was 13.3. Can I trust these results, could my kit be bad or am I doing something wrong? I have to believe something is wrong in my tank since my coralline is going away, but can reef crystals salt really be off the chart in dKH?

 

[odyssey1]

Wow not sure about reef crystals because I use Instant Ocean. I havent heard of anyone posting anything about reef crystals being that high something dosent seem right!

Have you checked the water you are mixing it with? Are you using RO/DI water?

I would check the water first that can and most likely is the problem. However if your DKH in the salt mix is 13 and you are only adding 10-15 gal your tanks DKH shouldnt change that much maybe 1 point or so.

My tank runs around 9-10 depending on the day!

 

[odyssey1]

How is the PH? These calcium and Alk levels will be a direct effect on the PH. THis could be what is causing the problems in the tank!!

Make sure the PH is stable. I wouldnt worry too much about the exact levels in the tank as much as the stability (levels staying consistant) expecially the PH.

It is good to look at the cal. and alk. levels in your system but you need to keep the PH around 8.0-8.4 at all times. Too high or worse too low cill cause the problems.

 

[rfdoc]

Yes I'm using RO/DI water and the pH is always between 8.1 to 8.3 measured by a pinpoint probe. It has been dropping a little since I stopped dripping kalk however.

 

[crvz]

Hard to say if you're doing anything wrong, but if the measurement was that far off of the "calibration" fluid then I'd suspect the test kit or your method over an actual dkh issue. Seems odd that the number fluctuate that quickly, and as pointed out RC salt doesnt have that much alkalinity any time I've tested it (I've been using that salt for the last 2 years).

 

[rfdoc]

Thanks for the replies. Any other thoughts? I'll test my RO/DI water tonight, other than that is there anything else I can test to see if my readings are accurate and what's causing my coralline to die?

 

[Yogre]

I've read here on RC about Salifert alkalinity test kits being squirrely from time to time. I had one that did the same thing yours did...KH over 16 and the check solution at 13. I used an API kit and got a result of 11 for freshly mixed Reef Crystals, about what I would have expected. I tossed the Salifert kit.

I think I'd check your salt with another kit brand before taking any action.

 

[jkst06]

I just ditched my Salifert ALK test for the same reasons...I've tested it with 2 other kits and the Salifert was reading from 1.2 - 2.4dH HIGH!

 

[rfdoc]

I tested with an IO kit tonight and I'm reading the fresh batch of saltwater at 8.4dKH. That seems lows, I can't win??

 

[rfdoc]

My tank is now testing at 6.3dkh with the IO test, and around 13 with the Salifert. I don't like either number. Which do I trust and can someone recommend a reliable Alk test kit? I thought Salifert was recommended here, maybe I just got a bad kit?

 

[GW81]

are you using them correctly? When the syringe is fillied, I know that salifert's black plunger should be at 1.0, but the actual fluid doesn't start until .8.

 

[Toddrtrex]

<a href=showthread.php?s=&postid=14824265#post14824265 target=_blank>Originally posted</a> by GW81
are you using them correctly? When the syringe is fillied, I know that salifert's black plunger should be at 1.0, but the actual fluid doesn't start until .8.

Quoting for importance. With drawing in the one reagent with that 1ML syringe you do NOT clear out the air.


EDIT -- this is a picture from the Cal test, but still works for Alk, this is what the one syringe should look like after you have drawn in the reagent, and before you start putting it into the vile. You can see that the liquid stopped at .75 ML

 

[rfdoc]

Yes I'm following the instructions for both kits.