Does anyone have a Merc/D-D PO4 test kit?

[Delphinus]

Does anyone have one of these?
http://www.jlaquatics.com/phpstore/s...duct_ID=t-dpo4

I have a phosphate meter but I'm getting some very strange strange results and I need to either test a known reference sample, or do some comparative samples to see if my results are valid.

Long story short, I don't trust most test kits anymore and I'm starting to distrust this electronic meter as well. The Merc/D-D testkit has a strong reputation for high-senstivity in low-range phosphate values so I would like to see how my meter stacks up to it.

[Ruth]

Tony what kind of meter do you have. I have a Hanna colorimeter and from the looks of my work schedule will be in Calgary a couple of times in the next month or so. I could bring it down with me if you like but I will be staying downtown so you would have to come and get it and bring it back. I think I will be there for 4 days in the middle of June.

[Delphinus]

Beggars can't be choosers .. I'll come find you.

Sounds like we have the same unit ... I'm really disappointed that I'm getting such inconsistent results with it so I don't know what's going on, either I've got PO4 worse than I ever imagined or the thing is just faulty (wouldn't be the first time, I had to send my nitrate meter back because it wasn't working right), or I'm doing something wrong.

For example, get a load of these results:
- Tank 1: PO4 = 0.10 (this is the tank that can't keep SPS alive no matter what). Topoff is RO/DI.
- Tank 2: PO4 = 0.08 (this is the nitrate disaster tank). Topoff is tap water.
- Tank 1 Phosban reactor effluent: PO4 = 0.11 (higher than the tank water??)
- My tap water: PO4=0.05
- My FW tank: PO4=0.13 (tap water)
- My RO/DI: PO4 = 0.23

The thing that has me absolutely stymied is the reading of 0.23 of my RO/DI. The TDS of the RO/DI output is zero so I was under the impression that it was working fine. Having wrecked several membranes I've now learned to keep a close eye on the TDS just to be sure I'm not wrecking this one. But to have input=0.05 and output=0.23 ?? Now I'm just suspicious of everything. Granted I tested the water that sits in my reservoir and not fresh output, but 1) the water is no older than a couple days and 2) where would the PO4 even be coming from?

I'm so confused. I don't talk much about my lack of SPS these days on the board but I find it completely demoralizing to know that I've had to give away (or watch die) every acropora, every montipora, in short every SPS I've ever had (some that I've had for years and years), because that they just don't live. They grow a little, then boom, half will succumb to RTN or STN. Then they grow a little more, then boom, another half will succumb. Eventually the math catches up to them and there's nothing left. I *thought* it was a phosphate issue because I don't see what else it could be.

Ahhhhh I digress. The point is, I don't understand why the readings are so over the map. Once I can get zero readings for PO4 on my tanks (and have confidence in the readings), if I still can't keep SPS after that, that will be a bridge I jump off another day. For now, the immediate goal is to figure this PO4 crap out.

[Der_Iron_Chef]

That's completely puzzling. My only conclusion would also be to assume the instrument was faulty. How can effluent from the Phosban Reactor be higher than the tank water?! That's bizarre.

I'm curious about something...what's your PH? I recently read an article in reefkeeping magazine that said low PH levels help deliver phosphate into the water column. It also said that live rock which has been exposed to high levels might act as a resevoir. As well....inhibit calcification, which is especially pertinent to SPS.

Anyway, I'm sure you know all of this, and it doesn't help to explain the perplexing nature of your readings.

[trilinearmipmap]

I have the Merck test kit and if you mail me a sample of water I will test it for you. PM me if you want to do this.