Test Kits Different Quality?

[lagreca]

I recently bought a Taylor K-2006 test kit, which was fairly expensive (~$45). A few days later I was wandering around Walmart, and ran into an HTH 6 way test kit for $22.47. Is there a reason anyone should stay away from the cheaper HTH kit from Walmart?

[chem geek]

$45 is actually a good price for the K-2006 -- usually it's discounted to around $56. Are you sure you got the right kit? Where did you get it?

The HTH 6-way is not the same, primarily because the Taylor K-2006 kit has a FAS-DPD chlorine test that is more accurate and easier to get right compared to the OTO test in the HTH and other less expensive kits (this link implies that the chlorine test is OTO, but some other kits use DPD). With FAS-DPD, you count the drops until the sample turns from pink/red to clear while with the DPD test you compare the intensity of color against a standard. The FAS-DPD with a 25 ml sample size has a precision of 0.2 ppm for FC and CC and an accuracy of better than 10% or 0.2, whichever is greater. Also, FAS-DPD does not bleach out at 5 ppm or 10 ppm as any "flash of pink" just needs additional powder so one can measure up to 50 ppm if need be -- DPD tests can bleach out while OTO tests do not.

The pH test in the Taylor kit has a special combination of chlorine neutralizers designed to not affect the pH up to around 10 ppm FC. I'm not sure if the HTH kit does that.

If the HTH test kit you have uses an OTO chlorine test, then it is the least accurate of all (less accurate than DPD) and the intensity of yellow is usually very hard to match. At least the OTO test does not bleach out at high chlorine levels.

Also, it looks like the HTH test tests for Total Hardness instead of Calcium Hardness so that's pretty useless for calculating the Calcite Saturation Index you need to know to protect plaster surfaces (for a spa, the CH is mostly to prevent foaming).

Basically, you get what you pay for since the OTO test is less expensive than DPD which is less expensive than FAS-DPD. Also, Total Hardness is less expensive than Calcium Hardness since it doesn't require an extra reagent.

[lagreca]

I bought it at Amazon: http://goo.gl/iK0cnn on Jan 19, 2014 for

Item(s) Subtotal: $48.00

Shipping & Handling: $5.41

Total for This Shipment: $53.41

But it looks like the price has jumped back up again. It's now $70 + $8 shipping!

I didn't buy the HTH kit, just wondering about it. Thanks for explaining.

Where would be a good place to buy replacement reagents for the Taylor K-2006 kit?

[chem geek]

SPS pool supply used to have good prices, but I can't find them anymore so you can try TFTestkits.net or Amato Industries.

[dlleno]

+1 on Amato for me anyway. when I bought my 2106 it was from Amato via Amazon because they priced it more attractively there. But I find that the reagents via Amazon's various outlets are more expensive than going through Amato directly.