Pool testing device - digital preferred - advice needed

[mhca]

I'm so glad my pool isn't in Denmark! I wouldn't be able to keep within the law. You definitely need automatic dosing to keep everything in such tight ranges, and we don't have that.

Since you will be measuring FC at around 2ppm then I think you do need a photometer. They work really well in that range, and having digital measurement eliminates variability due to bad eyesight, colour blindness or lighting. We use a Lovibond checkit 3 in 1, which is their basic model that checks FC, pH and CYA. I like the CYA test very much. It seems less subjective than the black dot test so long as you have a consistent technique (you have to shake it up and retest a few times, the equivalent of pouring it back and forth in the black dot test).

We use a tablet count method for TA and CH which is a tablet version of the tests they recommend on here where you add reagent and look for a colour change. Those were very cheap to buy.

Yeah, it has been a pain in the butt till now just to have authorised that we can suffice with a turn-around-time for the water higher than 2 hours. The rules for a pool below 1.50 m depth requires us to recirculate the water in 2 hours or less. For our pool that is theoretically 26 m3/h. Luckily we have been approved to just stay below 5 hours, as our pool is almost 1.50 in depth.


Regarding the photometer, I think that is also the general opinion... that we need something digital... and we need it pretty soon actually.

However, there is general attraction to the eXact Micro 10 photometer. It is a shame that I cannot find any user reviews or similar indicating if it's worth it.
The eXact seems a lot more simple to use than having to handle a vial, carefully filling the correct amount, avoiding fingerprints etc. as is necessary with the Lovibond Checkit / MD200.

BR, Martin

 

[loop_pea]

Regarding the photometer, I think that is also the general opinion... that we need something digital... and we need it pretty soon actually.

However, there is general attraction to the eXact Micro 10 photometer. It is a shame that I cannot find any user reviews or similar indicating if it's worth it.
The eXact seems a lot more simple to use than having to handle a vial, carefully filling the correct amount, avoiding fingerprints etc. as is necessary with the Lovibond Checkit / MD200.

BR, Martin

According to here: http://www.worldofpools.com/exact-micro-10-details.htm this tester has an accuracy on the pH of + or - 0.3. That's a huge range. If the tester reads 7.5, that means the true pH could be anywhere between 7.2 or 7.8. I think you need to know where you are more accurately than that.

I don't really understand the technology they're using, but this seems like a machine that reads test strips, and test strips are not normally a good way to test your pool. I watched the video and the water had a TA of 13ppm. That's a very odd number.

Also it looks like the reagent strips are fairly expensive.

 

[Stuamurr]

Ditto loop_pea, If I was you I'd go for the MD200 6 in 1, tests everything with high precision, and the re-agent tablets are relatively cheap, costing around 1 pence per test tablet, especially with such low chlorine parameters.

"you get what you pay for" certainly springs to mind.

Regards
Stuart

 

[mhca]

Thanks for the link loop_pea. I hadn't searched very thoroughly, but I actually wanted to find some specifications about its accuracy.
Regarding the use of strips, I don't think you should compare it with regular strips. I think it's just their way of releasing the reagents.

I actually wasn't too worried about the pH, but only having a range of 7.0-7.6, that means that I need to be right on 7.3 to be sure to have a reading which isn't outside the range, when I have an inaccuracy of 0.3.

The eXact Micro 10 has an accuracy for chlorine of
0-3 mg/l: ±0.05
3-7 mg/l: ±0.7 !!!
Based on that higher interval, I would be a little worried about the actual accuracy for chlorine. I guess it isn't truly 0.05 through the whole 0-3 mg/l range.

I found the accuracies / tolerances for the Lovibond MD200 when using tablets:

pH: ±0.1

Chlorine:
0 – 1 mg/l: ± 0.05 mg/l
1 – 2 mg/l: ± 0.10 mg/l
2 – 3 mg/l: ± 0.20 mg/l
3 – 4 mg/l: ± 0.30 mg/l
4 – 6 mg/l: ± 0.40 mg/l

Being in the interval close to 1-2, it looks nice to have an accuracy below ±0.2.



I have a question about the Lovibond. On page 3 in this pdf can be seen the various versions: http://dl.lovibond.com/cat/en/cat_md200_pool.pdf
What is it that we really need to be able to measure with the 6in1 which should make us choose that over a 3in1?
3in1 would be one for pH, Chlorine and Cya / Stabilizer.
Is it the alkalinity and calcium hardness which can be valuable measurements?
Looking at the 6in1 versions, I guess we don't need any of those, e.g. the bromine measurement, so we could probably suffice with 5in1 or 4in1 maybe?
I just need to know why we should consider a more expensive version than 3in1.

Thanks in advance

 

[JasonLion]

You want to be able to measure FC, CC, PH, TA, CH, and CYA at a minimum. You don't need to measure all of those using a single device, but you do need to be able to measure all of them one way or another.

 

[loop_pea]

I actually wasn't too worried about the pH, but only having a range of 7.0-7.6, that means that I need to be right on 7.3 to be sure to have a reading which isn't outside the range, when I have an inaccuracy of 0.3.

You'll never really know where you are with pH if the accuracy is less than the entire range that you're trying to measure. When the pool inspectors turn up with much more accurate kit, you might find that you're not compliant with the regulations.

I think you're right that the 4 in 1 or 5 in 1 will represent better value and cover the tests you need.

 

[Stuamurr]

The point I should of made was that with the difference in price between the MD200 models being so low, compared to the basic model price, you might as well get a model that tests everything you need to test, ie, as Jason says, FC, CC, TA, CH, PH, CYA, so I would surmise that to be the 5-1, but then if I was offered the 5-1 or 6-1 for little difference in price I would get the 6-1.

I would be surprised if your Envirnomental Health Officer or your countries equivalent didn't turn up with a Lovibond Md200 also to test your water!

Regards
Stuart

 

[mhca]

Thanks a lot all three (Jason, loop_pea and Stuart).

I think I'll get my neighbour to get a price on the MD500 5in1, hopefully today. If we can get a decent discount, it will maybe only cost the same as the eXact Micro10.

Stuart, you're personally familiar with the MD200... Do you know if the Standard Reference Kits are needed? They do seem to cost enough to make one consider living without them. And how do they work? Is it a simple comparison chart, or is is special reagents to test and recalibrate?

BR, Martin

 

[Stuamurr]

The reference standards are re-calibration titrants, you will only need them if you start getting inaccurate results in a photometer. If you have someone regularly testing independently of yourselves you won't be long finding out if there is a discrepancy, but I've never heard of or used the colour standards to re-calibrate, I presume they will operate the same way as the UK, in that they will give you a basic report on site of what their readings are (FC, CC, CYA, TA, CH, Ph) followed by a laboratory analysis for everything else.

Stuart

 

[mhca]

Thanks for all the replies till now.

We will most likely order the below today:

Lovibond MD200 5 in 1 (pH, FC, TC/CC, CY, TA, CA)
500 pcs DPD1
500 pcs DPD3
500 pcs pH, phenol red
1 extra glass brush
1 extra stirring rod

I have tried to find out how many tablets are supplied with the MD200 for CY, TA and CA. If it is 50 of each, then we believe we will not need additional ones to start out with. We only expect to measure those values once in a while, maybe every 1-2 weeks just to keep track of those values.

We couldn't get a very high discount from our supplier and the 5 in 1 costed 50% more than the 3 in 1. I had assumed it would only be 20% more.
But reading about CY, TA and CA we decided that we wanted to be able to have a test method we feel that we can rely on, whenever we wish to test those.


Stuart, I don't know how long you've used MD200, but Lovibond says that their tablets are high quality with a shelf life of 5 years.
Do you have any experiences with this? Do they still provide accurate measurements after 1-2 years?

BR, Martin

 

[Stuamurr]

I got a batch of lovibond tablets about 2 months ago so I'll go and check the expiry date on them for you shortly, I know we were always told to throw them out when they expire.

Shame about your discount not being heavier on the md200, but you will not be disappointed.

Regards
Stuart