DPD 3 Test Tablets - 250 Tablets

Palintest DPD No 3 reagent tablets in a box of 250, used with a DPD No 1 tablet to read total chlorine on a comparator or photometer. Once you have the total figure you subtract the DPD No 1 free reading to work out combined chlorine. Rapid-dissolve instrument tablets, not dip strips.

• Completes the total chlorine read after a DPD No 1 free test.
• Lets you calculate combined chlorine as total minus free.
• Dissolves quickly in the sample cell for a clean instrument colour.
• Delivers measured figures rather than a strip colour-band estimate.
• Fits straight into the comparator or photometer routine you already run.

Price

£24.95

How to use

1. First run a DPD No 1 test on a fresh 10 ml sample and note the free result.
2. To the same developed sample, add one DPD No 3 tablet.
3. Crush and mix until the DPD No 3 tablet has fully dissolved.
4. Wait the short develop time your method sheet states.
5. Read the total chlorine figure on the comparator or photometer.
6. Subtract the free reading from total to get combined chlorine.

Frequently asked questions

What does DPD 3 measure?

Used with a DPD 1 tablet it gives total chlorine. You then subtract the free reading to find combined chlorine.

Can I use DPD 3 on its own?

No. DPD 3 is a second-stage reagent; add it to a sample already developed with DPD 1 so the instrument reads total.

How many tablets in a box?

250 tablets, giving 250 total chlorine tests.

How do I get combined chlorine?

Combined equals total minus free. Read free with DPD 1, read total with DPD 1 plus DPD 3, then subtract.

Why does combined chlorine matter?

It is the spent fraction tied to the harsh chlorine smell and eye sting, so tracking it flags when a shock dose is due.

Do I need DPD 1 as well?

Yes. Every combined-chlorine result uses one DPD 1 and one DPD 3 tablet, so buy them together.

What about pH?

Use Phenol Red tablets for pH on the same comparator or photometer.

Why not just use strips?

Strips do not separate free, total and combined cleanly. The DPD tablet method gives measured figures for each.

What sample volume?

The same 10 ml sample you developed with DPD 1; add one DPD 3 tablet to it.

Total not developing?

You likely added DPD 3 to plain water; always develop with DPD 1 first.

High combined reading?

Shock dose to your site procedure, circulate, then retest free and total.