No way to obtain FAS-DPD Test

Oct 14, 2013
27
Harare, Zimbabwe
Hi Mike here from Harare Zimbabwe. :wave:

I have been reading this awesome site now for over 6 months, this is my first post. (sorry in advance for the length!!)

First of all my story is, I moved to zim about a year ago with my wife from the UK to live with my in-laws and try life the African way, so far so good! :cool:

One of the best things about moving (aside from the weather!) was having my first ever private swimming pool. Being the sort of DIY handyman guy I fancy myself as, I set about renovating and repairing the property that had been somewhat neglected (Pretty good fun seeing as we were used to a 2 bedroom top floor apartment that didn't really have much scope for such projects....) This included the pool which at the time had more problems then I can count. :shock:

As I started on the pool one thing led to another then to another etc. In the beginning all I wanted to do was get the Barracuda working I thought that would fix the green!! So far using the help from this site, to date I have completely replaced the leaky plumbing system with pvc, stripped and serviced the pump, disassembled and acid cleaned the filter as it was full of Algae, Cleaned the sand using the hose pipe method, Added the correct level of sand, the installers had only put in approx. 1/8th of the sand needed..., replaced the weir door, replaced the non existent pump and weir baskets etc etc I think you get the picture. Then that lead me to the chemistry side of things.

In the first month I was here I got pretty badly pool stored, which of course made things worse, but thankfully led me to the site. The main course of treatment on sale here is a pretty dodgy mix of powdered alum floc, zinc and copper. They claim with this treatment once a month for my size pool I only need to add 200g of cal-hypo a week . Im sure you can imagine how the pool would be green 90% of the time, cloudy etc :rant: . Then they sell you floc, clarifier, algaecide (no one here has even heard of polyquat 60....) you name it to rectify things. In the beginning even after the algae was gone I had to use crazy doses of sequestrate to clear the crystal light green pool because of the copper, (even the municipal water we fill with is undrinkable as also full of metal If its even treated at all…). At no point was CYA even mentioned, the temp here gets to at least 22 Celsius 365 days a year, even in the winter. The pool is in the sun all day. In the summer it gets to approx 36-38c daily. I know the actual temp does not affect chlorine loss but the sun is strong for a good 12 hours a day all year round. It was the typical merry-go-round of pool store advice you read about so often on here. When they do the "free water test" they only test the ph! Then from that somehow they work out you need all the products you can possibly carry. :grrrr: So that's the picture and as I say, not all bad as this lead me perfectly to TFP. I love this place I honestly do, my wife calls me obsessed!

So, to this point I have found everything I needed here to turn the green swamp I inherited to a sparkling oasis using purely BBB method. The bleach in the supermarkets here is horrendously expensive (500ml 3.5%= $5 USD) and often doesn't even tell you the %, as regulations leave somewhat to be desired. So I found a cleaning company that manufactures the stuff and I buy direct, according to the bleach cost calculator it’s a pretty good price. 25L 12.5% is 36USD. I also get my MA from them. My pool typically rises in ph over a month and requires half a jug to get things in check, even though I maintain my TA around 80. So I have been getting by using very strict calculations from the pool calc, and I think I may even have pool school committed to memory. To get my volume I took 100 measurements of the depth throughout the pool and used a water meter to work out the volume of the surface area by increasing the depth by 1”. A method I also found on here. Why so precise you might ask? Because there is no way I can get a FAS-DPD kit or CYA test. None. At least without paying $500+ USD to get it cleared through customs due to regulations etc. I am hoping to get a proper one when in-laws in the U.S. come to visit, but that will be in March next year. And the cost of getting one from family in the U.K. is almost as much as shipping here normally, and again they are not planning to visit until mid next year. :cry:

So in the meantime this brings me to my subject matter, is it possible to make my own test? There is a wealth of mining and chemical companies here that my line of business brings me into frequent contact with, and I wouldn’t be surprised if I could get the individual reagents made/ sourced for a reasonable price. At the moment I am relying on guesstimation with an OTO test (using the guide to extend the test to higher numbers), a DPD tablet test in the HTH 4 way drop kit ( TA, PH, Acid Demand and DPD tablet test), and test strips ( which I can confirm from my math’s are hugely unreliable-but at the time I didn’t know about the site when I bought them). If any one knows if this is possible I would be hugely appreciative. When I shocked for two weeks to clear the pool I had to use a ****load of bleach. I got it done but now things are just not economical and I have torn my hair out pretty much trying to get the numbers precise.

Trust me no one even knows what this test is here, let alone sells it. To give you an example of the limitations of stuff available here, in the entire country not one hardware or plumbing company I have talked with, has ever heard of PVC primer. I drive around all week visiting chemical plants mining companies and distributors for my Job so I have had plenty of scope to search. And I have found nothing. Hence now I am seeing if its possible to take a different approach and make one. But hey I have to be grateful there even pool stores in a 3rd world country right?
Something else I cannot source while on the topic is a CYA test. For this I had no idea on the level, but after 6 months of backwashing, evaporation, leaky pipes and splash out etc I figured it was safe to add pure stabilizer to bring to approx level of 40ppm. Ideally I don’t want to have to wait 6 months before I think its low enough again. I have read many stories of overdoing it here so have been extremely cautious with the stuff, luckily when I was pool stored I never used di-chlor or tri-chlor. I just worry about the use of floaters before I arrived, I know that they were using the copper treatment with no CYA exclusively for about a year before we moved, so I hope it was at 0 when I added. Ideally I want to maintain a level of 70-80 with the sun we have, but cannot do this safely at present. I have managed to acquire some tablets for the tablet based CYA test, but even in South Africa cannot source the testing tube. Is there a way to make my own one of these as well?

I know this is a big post that contains a few topics so sorry for that!! I hope you can see I have done my research and meticulously studied the site and pool school. I have searched the site the best I can and cannot find any post re making a FAS-DPD from scratch. As I say I don’t know if this is even possible so any help or advice is very much appreciated. I am sorry if this is posted in the wrong area, I thought as I have only just actually officially joined it seemed like the best place. My pool is sparkling, no problems other than using more bleach than I would like, and not being able to monitor CYA. I want to keep it this way hence asking these questions. It’s not realistic to keep going with BBB successfully and affordably without a proper test kit at this point, especially without the two tests I have mentioned.
Many Thanks in advance for you input in advance. :goodjob:

Mike
 
Welcome to the forum :wave:

Congratulations on taking control and learning and understanding.

Can you test the copper level? (sorry if I missed it)

You know we'd love to see some pics of the pool and surrounds :-D
 
hummmmm Is there any way one of us could buy/ship you the kit? I have NO idea how customs works so...... Say someone sends you a "gift" what happens? How much does it cost to get a "gift" through customs?

Kim
 
Firstly I have seen quick responses before on this forum but wow that was quick!!
I really appreciate the input :-D

Butterfly- Thanks for the welcome! Sadly I have no way to test the copper level, I can possibly get a test for this with one of the mining companies but it will likely be very expensive. All I know is that the water is clear and my 18month old son's blonde hair does not turn green! :mrgreen: Hope that helps- I haven't seen any copper staining and I am pretty sure the pool will have been at least 3/4 drained and refilled by now since using those treatments due to backwashing ect (plus when I did some tile repairs I drained a 3rd forgot to mention that), although the fill water does have metals in it :-| . I feel its not a problem but of course, without testing I can't be sure. If I can get a full kit with a way to test for that I will of course post the results straight away.
I will post some pics when I get home, currently at the office :wink:

Kimkats- Yes that could actually work, there is a specific way to list the details of the contents when shipping that I have used to get things like kids clothes and toys etc sent. (A plain plastic sippy cup for example here cost's 26USD... :!: ) Would be awesome if I could get my hands on the real deal! :whoot:

Again thanks in advance for all replies :goodjob:

Mike
 
Since you already have the DPD, albeit it in liquid form (which doesn't matter -- it just lasts longer as powder), all you need is ferrous ammonium sulfate (FAS) reagent. It's in a buffered water solution with a pH of 2.1. If you get pure FAS, it's usually in hexahydrate form (i.e. has water content in the light green crystal) as Fe(SO42-)2(NH4+)2)(H2O)6 or equivalently Fe(HSO4-)2(NH3)2)(H2O)6 with CAS# 7783-85-9 (or 10045-89-3 that one source had). You'd have to carefully create a very dilute solution of it -- how dilute depends on the volume of drops (Taylor kits have reagent bottle tips with 24 drops/ml) using deionized water.

Since one drop represents 0.5 ppm (mg/L) in 10 ml (or 0.2 ppm in 25 ml) this means that one drop has ((0.5 mg/L) * (10 ml) / (1000 ml/L)) * ((24 drops/ml) / (1 drop)) * ((392.14 g/mole FAS) / (70.906 g/mole Cl2)) * (2 Fe2+ / 1 HOCl) = 1.327 mg/ml as the required concentration of FAS hexahydrate. Technically, the back titration is just using ferrous iron so you may be able to use other ferrous substances (scaling to their molecular weight). Actual FAS reagent from some manufacturers may be ferrous ethylenediammonium sulfate (FEAS) and the Taylor FAS may contain some sort of stabilizers to prevent oxidation of the ferrous iron.
 
Re: Building a brand new pool in Nicaragua

I second the idea of looking for the "raw" chemical agents. I used to live in Venezuela, and I often did that. Chemical supply stores can be quite well equipped with chemicals to make reagents. You may have to borrow the use of a lab scale to measure chemicals.

Moved by moderator from HERE. I think this was the thread you meant to post in. If not, let me know. Thanks, jblizzle
 
Hi sorry for late reply, past few days have been crazy someone kindly decided to reverse into the side of my car so have had my hands full!!

Very pleased to hear that until I get my hands on the full TF100 I can attempt to make my own tests, :whoot: love this stuff. Honestly though you should have seen the wife's face when she read chemgeeks reply!

Chem Geek, thanks very much indeed for the detailed info, the dpd test is actually in tablet form so what I will do is find out the amount of dpd powder in each tablet and then make a solution of ferrous ammonium sulphate dilute in de-ionised water to the concentration you have listed below depending on the actual type of fas I can obtain, is that correct? From tomorrow I will be on the hunt around as I know what I am looking for (thanks again for this :-D ), to try and find some. When/if I do I will post/pm the exact details of it so that, if you would be so kind, you could please help me create the perfect (as can be) solution. This stuff is exciting! Geez I am such a nerd!! :party:

Dschlic- Really encouraging to see you managed to do this while living in Venezuela, it sounds like similar circumstances with regards to to obtaining pool stuff. Gives me hope!! I am sure I can make use of a lab scale I have a few contacts that should have one.

Thanks again to everyone has posted this help is as always invaluable, I intend to post on some other topics over the next few weeks/days as the Internet here permits.
I will also post pics of my pool.

Cheers from Zimbabwe
 

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Wow that is a very unique looking pool. At first I was thinking it had to be a vinyl liner, but then re-read your signature to see it is a tiled pool.

Is it rough at all with so many different shaped tiles and large areas of grout?
 
Thanks all u guys for the comments about the pool :-D made my evening!!

Bama rambler- I stumbled across pics of Robbie's pool a few weeks ago with the red bricks and tiled water line, I also thought to myself that looks strangely familiar...!
Was searching around for more info on removing small rust stains from tile (when the pool was used by my wife as a kid they used to dive for coins, must have forget a few once upon a time as there are 4-5 perfectly round coin outlines stained to the tile that no one really notices except me... tried to do vit c in a sock method limited success plan on doin aa treatment when get hold better test kit), the keyword's must have bought the post up. Small world!

Jblizzle- I think it probably would have been like that back when it was built, but 50 odd years of use later it pretty nice n smooth. Only places grout gets a bit rough is where the pool cracked about 20/25 years ago and had to be repaired, and the edges of the steps are a bit sharp in some places. Not really noticeable unless your looking for it. Will take pics another day of the repair its pretty clear to see, goes from back right corner area all the way down to around the centre in a diagonal line. Apparently the builders back in the day were a British firm (zim was a British colony then for those that are not aware) and offered a 30 year guarantee, so they sent a diver to look at the problem and attempt an underwater repair. Must have been pretty cool to see. Don't know about in the states but here now you are lucky if you get a year guarentee included! Bit of history there about my pool for anyone who might have been interested! :study:

Back then it used a solid metal DE filter, now sadly you can't even buy pool rated DE powder in the whole of Southern Africa it seems, let alone a DE filter itself. (Believe me I have tried!!)
 
Hi Mike.

How is the FAS-DPD test coming along? That's pretty resourceful of you to try and come up with your own.

I've left you a PM asking where you get your bleach from. (I also live in Zim so would really appreciate a decent source of the stuff).

It's a pity we can't get CYA tests here. As you say, not many people here have even heard of them.

Thanks very much.
 
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