Testing with inconsistent results

[pnikiel]

I'm becomming convinced that testing aquarium water is an inexact science.

I just got done testing for Alk., CA and Mg. I have three different test kits for Alk. I started with a NatuReef kit (which is what the lfs always uses) and the first test showed 3.5 mew/L. That seemed low so I tried it again and it came out 3.75. A little better.

I have two Salifert kits for Alk. One dated to 2010 gave me the same result, 3.7. One dated to 2012 tested at 4.2, twice.

So is my Alk high or low?

Two tests with my Salifert CA kit showed 380 adn 390. Should I try to raise that?

Two tests with my Salifert Mg kit... both showed 1290. Should I try to raise that?

It seems to me that my experience with the Alk testing shows there is a range, but I got results on both ends of the range. And that makes me wonder how to interpret the other tests I ran.

Does anyone know how to make testing more exact?

 

[NaH2O]

There have been a few folks with Salifert alk test issues with new batches. You might check this thread: measure KH. There is a link to a reef central thread about the alk test kit issues.

 

[Boomer]

and the first test showed 3.5 mew/L. That seemed low so I tried it again and it came out 3.75. A little better.

Kits can only be so accurate / $$$ but shoudd not be off this much

Two tests with my Salifert CA kit showed 380 adn 390.

This is within the limits of accruacy and a 10 ppm difference is meanlingless.

3.7. One dated to 2012 tested at 4.2, twice.

This is not and is a concern.

As Nikki has stated there have been lots of issues with Salifert latley. Habib has been very sick.

 

[Scooterman]

What would be the next reasonable test kits that is fairly reliable? I'm fixin to gern shopping soon!

 

[Boomer]

We have seen good results with the API. One could also try the Elos. Then there is HACH and LaMotte but you will have to get use to their expressions and the way of doing things.

 

[Scooterman]

I have an old LaMotte but they are expensive also! Maybe I can get a refill!
Tanks!

 

[NaH2O]

Scooterman - you can buy LaMotte's refill kit, instead of buying the whole shabang again.

 

[HarleyDude]

I have been going through the inconsistancy issues with the Salifert Alk tests as well. Habib from Salifert is investigating this and has posted on RC. I purchased a Seachem test which tests Total, Carbonate and Borate Alkalinity - well it actually just tests total and borate which you can equate the carbonate from. However, that test was faulty (I think) as one of the chemicals does not do what it is supposed to. I need to call Seachem to find out if there was a mistake. I attempted to get a LaMotte test and no one seems to have them in stock. These would be the only three I would really trust - where to now?

 

[DonW]

I wouldnt stress to much about the test kits. Most if not all of them are off in one way or another. Keeping parameter somewhat in the middle between high and low will allow you the room for testing errors. Trying to keep things stable is a much bigger concern, test kits are just a guide. Test often so your not caught in the dark wondering if its the kit and making big chemistry adjustments.

Don

 

[HarleyDude]

I agree Don, however I started to have some issues with depleted calcium and discovered that my Alk had risen and was causing the issue. I am trying to keep as close of an eye on it as possible and in my system there is a fine line with adjusting the Alk and not dropping the pH too far. A portion of the problem is an over abundence of CO2 in the house. Not sure where, how or why, but if I leave the windows open for the day my pH jumps.

 

[DonW]

I agree Don, however I started to have some issues with depleted calcium and discovered that my Alk had risen and was causing the issue. I am trying to keep as close of an eye on it as possible and in my system there is a fine line with adjusting the Alk and not dropping the pH too far. A portion of the problem is an over abundence of CO2 in the house. Not sure where, how or why, but if I leave the windows open for the day my pH jumps.

May also be nutrient levels. You should be able to leave keep your steady irregardless of ph. If you can keep ph at 7.8 or above your fine. Just testing frequently will clue you in as to wether or not a test kit is going bad.

Don

 

[Boomer]

Don

Where you napping when you posted those first two sentences

May also be nutrient levels

Did what ? Raised his Alk and or depleted his Ca++ and/or the pH jump had nothing to do with the windows

A perfect statement
I wouldnt stress to much about the test kits. Most if not all of them are off in one way or another. Keeping parameter somewhat in the middle between high and low will allow you the room for testing errors. Trying to keep things stable is a much bigger concern, test kits are just a guide. Test often so your not caught in the dark wondering if its the kit and making big chemistry adjustments.

HD

Seachem test which tests Total, Carbonate and Borate Alkalinity
There have been some issues with this kit.


The Seachem Borate Alkalinity Test Kit
http://www.advancedaquarist.com/issues/june2003/chem.htm

Then there is the Salifert kit

The Salifert Boron Test Kit
http://www.advancedaquarist.com/issues/sept2003/chem.htm


On room air CO2 and low pH

Low pH: Causes and Cures
http://reefkeeping.com/issues/2004-09/rhf/index.htm


Indoor CO2 Problems
http://www.advancedaquarist.com/issues/apr2002/short.htm

well it actually just tests total and borate which you can equate the carbonate from.

There is really no need to measure Borate unless you are using SeaChem salt, which is high in borate and can skew your Alk readings, which need to be corrected. With an Alk of 2.25 meq/ l only about .15 is borate for most salts.


Habib from Salifert is investigating this and has posted on RC[

Was this recently I hope ? He has been MIA for months.

 

[DonW]

Don

Where you napping when you posted those first two sentences

I just meant that low ph can be caused by excess nutriens also and you shouldnt have to play around with alk to maintain ph. I guess I should write in more complete sentences.

Don

 

[NaH2O]

Was this recently I hope ? He has been MIA for months.

Boomer - he's back, but has to limit his time online somewhat: Habib are you back?

 

[Boomer]

OK Nikki
I hope he fixes things quick as Salifert is going down hill really fast on reputation.

Don

He has high room air CO2, I'll bet on it.

And I of all people should not be picking on one when it comes to sentences :lol:

 

[DonW]

OK Nikki
I hope he fixes things quick as Salifert is going down hill really fast on reputation.

Don

He has high room air CO2, I'll bet on it.

And I of all people should not be picking on one when it comes to sentences :lol:

No, I know I believe it is also, just dont want anyone to think its the only cause. Just a statement, not cause or correction.

Isnt it your nap time?

Don

 

[HarleyDude]

Thanks guys - I definitely do not stress over the tests. I am just attempting to do two simple things. 1) Maintain Ca++ as recently we have not been able to keep it above 300 -- because of the Alk and 2) Stabilize our pH. With the one Salifert test, it did not even read on the chart for a while, which yes, did stress me a bit. We bought a second one and it was around 7meq/L.

Having said that, as soon as we did get the Alk back in line the Ca++ went right back to normal . However, by doing that it lowered pH -- which makes sense. Anyway, we found part of the issue which was we were buffering our DI water before salting it and throwing the Alk off. We are now just buffering evap/kalkwasser water and just giving it time to make a difference through water changes. I don't like to make any knee jirk "quick" changes when it comes to chemistry.

Boomer - thanks for the articles - I am a huge RHF fan and have read just about every article he has posted - some close to memorized as I have to read some a few times to understand them :idea:. The only article in that list I haven't run into was the last one and thanks I will go through it. With the Seachem test, the total Alk is the one that is faulty/doesn't work and that is the one I need. You're right, I could care less about the borate, but I figured I had it I might as well try it. I received this test because LaMotte was out of stock. You can see my pH trend on my web site and it is pretty obvious when I have my windows open. http://www.allensaquariums.com/reef/livestats.htm. For example, select the pH graph and for the Last 7 Days - I had my windows open Monday and Tuesday because it was cool and Tuesday afternoon we closed them. Can you say dive?
Oh - one more thing. I have two 180-gallon tanks (reef & puffer). They are both monitored by my ACIII (one with a PX1000 extender) and the reef's sump is in the basement, the puffer sump is under the tank in the living room. Their pH pretty close to parallel each other which was another indicator to me that there is a CO2 issue.

Don - 7.8pH from a technical perspective should be fine, but I have a few coral that immediately start to show signs when my pH drops below 8. One is a Sinularia and the other is Capnella. I can't say I have seen this in other tanks, but over reptition of seeing it, it is my only explanation.

Thanks again.

 

[Boomer]

Allen

That Alk still bothers me. I would guess you are in the high 3's which is fine. I dint' buy that 7 meq/ l based on the other tests. Corals find it difficult to calcify with you water parameters, particularly the pH. Ca++ does not matter as long as it is around 360 or higher.

What are you using for additives, Alk, pH and Ca++ and when was the last WC change and how large ? When the Mg++ is up to par and one has issues like yours, it is usually a ion imbalance issue which WC's fix.

 

[HarleyDude]

Allen

That Alk still bothers me. I would guess you are in the high 3's which is fine. I dint' buy that 7 meq/ l based on the other tests. Corals find it difficult to calcify with you water parameters, particularly the pH. Ca++ does not matter as long as it is around 360 or higher.

What are you using for additives, Alk, pH and Ca++ and when was the last WC change and how large ? When the Mg++ is up to par and one has issues like yours, it is usually a ion imbalance issue which WC's fix.

Yes, the Alk being that high (7) was a red flag that something wasn't right. The second Salifert test showed 5.11 and I still wasn't 100% sure it was accurate. So, I did a couple experiments using 2-1/2 gallons of pure water and testing all parameters, adding buffer, then adding salt to find that the buffer and salt together jacked up the alk, but left the pH still fairly low 7.6. With 24 to 48 hours of aeration the pH was at 8.2. I also did the same experiment w/o the buffer and after aeration everything was in check.

Now for water changes, we do 10% weekly. The display is 180gal and with the underlying tanks we total around 280gallons. So, we do about 30 gallons weekly. This tank was a 72 gallon for about 2 years and thrived with the same processes we are currently using. We upgraded to the 180 and included a 55 gallon RDSB tank and everything was fine for a while. The other comment that has been thrown in is a possible bad batch of salt -- we use IO and I have never had a problem with them, but....it is possible.

I have a Ca Reactor that I just got and have not hooked up yet as I want to stabalize everything before adding another possible issue to the mix.

Oh, to answer your question about additives. We now buffer only the evap/kalkwasser bucket, strontium, kalkwasser for evap and the salt which has additives. The strontium adds Alk too, but again this has never been a problem in the past. Once I start using the Ca Reactor I will most likely stop adding strontium.

 

[Boomer]

Baking soda buffers and most buffers have lots of BS, will add CO2 which will lower the pH for a few hrs until it is "blown-"off and is why you got those results. Take a liter of RO/DI water and raise the Ca++ to 40 ppm with Kalk. The Alk should be around 2 meq/ l. Also 1 level teaspoon of BS will raise the alkalinity in that 25 gallons by .8 meq/L, so 5 gal = 4 meq/ l