More water param questions?

[Djplus1]

Ok, I'm not the biggest tester in the world (just decided to check for the heck of it after about 6 months), but I will say, I do feel a little alarmed by the results and the multiple different results from 2 separate test manufacturers.

 

So I have been running a mixed reef and it looks pretty good in my opinion, aside from a pesky cyano issue that is probably related to a too much light issue.

 

Water was last changed  (10g on 72g tank with 10g sump) on 5/27.

 

Before water change on 5/31

 

Nitrate .5 Red Sea

Phosphate .04 Red Sea

SG 1.026

Mg 1200 Red Sea

kH 3.9 dkh Red Sea

Ca 300 Red Sea

 

Tested again on 6/2 right before W/C (Just the reef params)

 

Mg 1440 (RS) 840 (Salifert)

kH 3.9 dkh (RS) 4.1 (Salifert)

Ca 310 (RS) 430 (Salifert)

 

Water change 6/2 of 10g

 

Tested just now 6/3

 

Mg 1120 (RS) 840 (Salifert)

kH 4.8 dkh (RS) 5.1 (Salifert)

Ca 310 (RS) 460 (Salifert)

 

Other than the obvious need to dose ASAP, what's with the insane difference between the test kits? I bought the RS kit late last year, expires at the end of 2014 or early 2015.

 

The Saliferts came from a member used, so I place more trust in the RS tests, but the exp dates are 9/14 on mg, 3/16 on kh, and 4/16 on Ca.

 

I still maintain that salt water test kits are all trash and everyone just picks the ones that gives them the number they want to see and stick by it, but if I want to dose properly, I do need some sort of semi accurate start point. Aside from "buying new test kits to confirm that these practically new kits aren't off", what am I supposed to do here?

 

 

 

 

 

[ctenophore]

Salifert alkalinity should come with a reference solution.  What result does it give?

 

Personally, the only water test I use is a salifert alkalinity kit (well, also a refractometer).  I have not tested it against its reference solution (this is a fairly new kit), but it gives values very close to the old kit which I did test against reference.  I think that as long as the level is reasonably close to correct, you're more concerned with stability than a particular value.  Hopefully the kits can at least give repeatable values, whatever they may be.  So if things look good, and your kit says "460" calcium, as long as you keep it near that value, I'd say you're on the right track.  However, your alkalinity is quite low assuming salifert reference soln checks out.  I typically see sps tissue loss below 5 DKH, so if you are not seeing that, then maybe the accuracy is suspect.

[gmerek2]

Well IMO they are just a guideline. Why I think they are off? The amount of water we use is a tiny tiny bit.. When you measure 5cc of saltwater even 1 drop extra can throw things off a little. If I push on the syringe plunger hard I can get 2 extra drops. If I rinse before use, there is 2 extra drops total on test tube walls. If you forget to rinse with RODI, there is 2 extra drops of dried ca mg etc. just my opinion even the electronic ones have variants.

[Djplus1]

Additional info. I use Red Sea coral pro salt. I also added a heaping dim sum spoon of kalk to my stirrer yesterday with the water change.

[howaboutme]

Sounds like a similar situation to Isaac and I...my alk only dropped to ~ 5 dkh. I was testing w/ red sea and then got the hanna...(and also used Api for verification), the red sea was fine. I'd just pick a test kit that you know is giving you relatively accurate results and stuck with it. Only use others to verify an off number. I like red sea because you can just buy the reagents.

 

weird that your kalk wasn't keeping up w/ your alk consumption...how often was your top off running do you think?

[Djplus1]

I also prefer Red Sea.

 

As far as the top off, I'm not home all the time, but when I am here it runs several times a day. I wasn't really adding kalk to any formula, just dumped a cup in the Stirrer to start which I clean out every month to 1 /12 months and add a big spoonful once a week.

 

My pH is fine, usually about 8.3 even with the doors closed and AC on, so I don't want to increase kalk too much.