Ca - Salifert says 270, Elos says 450
 

Which would you believe?

The Salifert is older than the Elos (by purchase date) but it's not past its expiry date. The Elos expired in April 2011, I didn't realize this because the SKU sticker was covering the date .. But was purchased well after that date so it was on the shelf like that.

I'm more inclined to believe Salifert because of the expiry date .. Would you concur?

It's annoying because either way requires an adjustment but would be fairly suboptimal to adjust things the wrong way. :neutral:

Tomorrow's payday, maybe I'm picking up a Ca checker. I might as well throw another wingnut value in the mix to really keep things confusing. :lol:

I would say if you are dosing calcium 450 would be the more accurate result but if you are not then I would say the lower one.

Unless you haven't done a water change in forever, 250 isn't gonna happen. You don't have 30 pounds of SPS in there, so I'd go with the 450. Then I'd go to the LFS and get it tested again.

Well .. consider the history though, this tank doesn't particularly behave in typical kinds of ways. Water changes also are happening, but currently at a rate of about maybe 8% per week. I sourced me a bigger bucket, 55gal, which should make it more like 15% per week but I have to revamp the room to make this thing fit in there. So for now water changes are possibly too small. Next, considering that the tank was humming along in steady state until a couple months ago and suddenly the Ca depletion rates stopped, so I had to back off the Ca dosing quite a bit to remain at targets. Fast forward another couple months and during that time trying to reduce phosphates, is it possible the Ca consumption started up again and I missed the point at where it started to drop? But that would be a bit unexpected because although the tank LOOKS better (way less hair algae, corals look better, evidence of growth in some corals, etc.) the PO4 test reading is still pretty high (0.18 tonight). Unfortunately there's no reason to suspect testing error on the PO4 as the checker gives a zero reading on the FOWLR (there's irony for you. The lesson learned is "stop caring about parameters" I think.) :crazyeye:

All conjecture until I can get a confirmation of one or the other Ca readings, I guess. I finished off the Salifert tonight anyhow so due for a new test kit. I might as well try a checker, they're only $20 more than the Salifert, and as for Elos .. I like them but this is not the first time I've taken home a test kit only to discover the expiry date being in the past after I remove the SKU. Maybe it's fine past the expiry to a certain point but who knows how long.

I make a point of checking expiry before purchase Tony. I've found expired elos kits in several lfs and started checking after purchasing two expired kits once.

Tony, why not just take the water in and have it checked at the LFS? I'm sure you can find something less frustrating to spend your $30 on :razz:

test a new batch of water.....you should know close to what that would be...than go with the more accurate kit. My guess is that the salifert is messed.

Not to hijack but I am having the same issues with my Ammonia test kits. Three different brands and three different results. I even tested new pre-mixed SW from before I did a water change and had different results. WTF?

Under 300 seems really low. I think if that reading were accurate you'd see some issues showing up.

Personally I've never used an ammonia test kit. After the initial large cycle you should never see any. And if you are just starting up a tank.....look for nitrite (never even tested for that one) at zero and nitrate to plummet to a respectable level. Really just testing NO3 will tell you where a tank is at in terms of the initial cycle.

Filefish dude.