Faint brown stain on pool bottom

[f1steveuk]

After taking a while to get the pool nice and clear (we haven't got home for quite a while), I can now see faint brown stains on the pool bottom.

Having cleaned the sand in the filter, it looks for all the world like little "drifts" of filter sand, but it doesn't hoover up, and can't be brushed. I am assuming that it may be caused by leaves, as we we got home, after a three month trip to the UK, and I re-commisioned the pool, I hoovered up a fair few leaves.

Will chlorine slowly remove them, or do I need to treat it in some way (and I don't mean to a nice meal and a film!!).

Ta

[Théière]

Hi Steve,

Can you define won't vacuum up and cant be brushed are they stains on the liner?

If it is little drifts then they could be fine dirt passing through the filter, if so they usually lay in front of the return jets only unless disturbed.

Any pictures? and water figures

[f1steveuk]

No, they look like little drifts, but aren't. So you think they will vac' up, but don't, if you see what I mean. Then if I get the brush to them, they don't brush away, so they are obviously a stain of something?

Chlor is perfect, ph is spot on, now. though it was high, but not by much. I just looked again and there are several of these discolourations, in different spots. Shallow end, deep end, but none on the sides, which is why I am wondering if the leaves that I scooped, then hoovered out, may have been the cause?

[Théière]

Hmm, organic remnants can stain but usually go with the chlorine over time. As ever it would be useful to know if you use multi action gallets and what the cyanuric acid (CYA) level is as that will determine how much active chlorine you are likely to have. At this time of year we begin to get algae blooms and some of these are not the common green variety.

Some stains can be iron from well water sources also copper stains as multi action gallets often contain copper sulfate (small blue flecks in the gallets) which over time can build up and drop out of solution as PH rises. It may be worth you placing a vitamin C tablet on the stain for a half an hour to see if that gets rid of it.

[f1steveuk]

Cheers Théière, I've really only got the pool clear this week after being here for three, and before that the pool hasn't really been touched since March, and even then the cover had been damaged letting all the leaves in, so I'm fairly confident it's stains from those, and I'm assuming the chlorine will get it now it has less work to do, although I may shock it again, just to make sure, although I also notice on the salt converter that the gauge is reading zero, though I think it always has!

[f1steveuk]

As the "stains" are growing, I'm guessing it's brown algae, especially as we have sunlight and lukewarm water, ideal for it, !!!

[Théière]

Well that's certainly confirmed it, mustard (yellow) and brown/black algae are harder to kill than green. The level of chlorine choc needs to be higher than for green and the surface of the algae spots needs scrubbing as brown/black type produce a tough out shell which you need to remove by scrubbing so fresh chlorine can get at what's underneath. and the level of choc needs to be maintained until it's dead otherwise it will just come right back.

Choc-ing a pool is not about the addition of a product called choc (fast dissolving chlorine) it is a process where you raise the free chlorine level high enough to kill the algae etc and hold that level with regular additions of chlorine until the pool is clear.

The level of cyanuric acid (CYA) has a very direct effect on how much chlorine is needed to kill the algae so knowing the correct CYA level becomes even more important.

 

[f1steveuk]

Shocked, level kept up, scrubbed, hasn't gone, hasn't got worse, puzzleing!!

I'm convinced some of the marks look like leaf prints, which is what made me think it was stains from leaf debris, and it only became noticable after I put salt in.

We go back to the UK next Friday for over three months, is there a long term solution, will it die off through cold in the winter, not being here is going to be a major problem!!

[Théière]

[quote user="f1steveuk"]Shocked, level kept up, scrubbed, hasn't gone, hasn't got worse, puzzleing!!

I'm convinced some of the marks look like leaf prints, Shame they don't resemble the virgin Mary or you could make a few bob [:D]
[/quote]

The only long term solution is to keep the chlorine level up and maybe a bit higher than usual, will you be running your salt chlorinator while you are gone, if not, I would add a copper based algaecide, not quatenary ammonium which isn't strong enough,unless you have a tiled/plaster pool in which case don't add it.

[steve]

CYA level? It could be high and all the chlorine in the pool wont work with high CYA.

Steve

[Théière]

Very true Steve, I noted it is a salt chlorine converted pool so unless stabilised salt granules were used the cyanuric acid (CYA) should be low (in theory) eventually the penny will drop that CYA is as important to measure as chlorine, total alkalinity and PH.

I have been in contact with Palintest to obtain stand alone cyanuric acid testers for people who require them.

[f1steveuk]

Yes the pool will be left ticking over, including the salt converter, and I use proper pool salt with some added bits (disifectant etc) made by Magiline I think.

It's all very annoying when you've tried very hard to monitor levels etc and the algae comes along to spite you!

[Théière]

Magiline is a swear word!

You have been using stabilised pool salt which means it does contain cyanuric acid (CYA) ( your disinfectant is chlorine, produced by your unit) it is quite likely that your pool is therefore over stabilised and so checking the CYA level is a must before you leave your pool to go swamp like in your absence.  What is the current level of chlorine and please don't say perfect as if that were true you wouldn't be having the problems you are now facing.

Don't attempt to measure CYA with dip strips they simply cannot do that accurately, in the spring I measured 3 pools with three popular available test strip and by the proper turbidity CYA test the actual levels of the pools CYA were 140ppm 160ppm and 190ppm (magiline pool) the test strips showed 20-30ppm and 0ppm.

Because some of your chlorine is chemically bound to the cyanuric acid (CYA) you need extra to be the active part, if you have 50ppm CYA the you need a min of 3ppm to an ideal 4ppm of free chlorine if your CYA is higher you need even more. Will you be putting your winter cover on before you leave, as that would help block the suns UV and so slow down any algae growth.

Sorry for all the questions but if want to get this right......

[f1steveuk]

Well with my very simple testing equipment, being just a pool owner, the levels are correct, but I suspect it can't be if tested with more professional gear?

I did notice today, that the water is the clearest it has ever been, crstal clear, which makes seeing the "stain/algae" easier to see. I also noticed that it has stain the skimmer surround and the jets up to water level. I tried scrubbing these, and it doesn't come off, so I remain puzzled!

[Théière]

Steve I wasn't having a pop, just re-iterating the need for reasonable test equipment as it would be for any technical hobby.

If all your tester says is perfick and not how many parts per million then it really must be from the bargain bin and that is that, the manufacturers cannot possible know the correct level for your pool.  You don't need professional equipment (until you get into trouble) [:)] I have spoken to Palintest today and test kits for CYA are on there way, not a fortune but still necessary.

Do you have any heater equipment  or pipe work that may contain copper or iron as there may be some staining from that. The crystal clear water sounds promising but if it is mustard algae that is another thing and using high levels of chlorine is the answer. Mustard algae would normally cling to the walls at all heights this sounds as though its metal stain, can you try a vitamin C tablet applied directly to the stain?

Any chance of a picture?

[f1steveuk]

I didn't see it as a pop, so no offence taken[:)]

I brought some "Algae Choc", and that appears to be slowly having an effect. It's not widespread, and not where you'd expect it to be, areas of poor circulation, steps etc, and I have now got a long term Algaecide, andI'm keeping the chlore levels up.

I totally agree with your comments on testing equipment. All the time everything looks ok, we trust the two little bottles of yellow and red liquid, then when it goes wrong, we're surprised!

I need to invent a single, hand held, electronic tester. One cup of water, and a read out of what needs going up, what needs going down, and how much of anything to put in!

Thanks for your help on this, sadly, we go to the UK Friday, so I suspect it will get away from me

[Théière]

Steve I would be interested on what's written on the packet of algae choc and long term algaecide (ingredients) if you have a minute as I don't know all the French products and I am always looking to broaden my knowledge.

EDIT:

The little bottles of liquid reagent well the chlorine one will lead you in the wrong direction. The OTO chlorine test only tests for total chlorine and not free chlorine. Total chlorine also includes the bad parts of the process (by products such as chloramines, trihalomethanes and cyanogen chloride) so you could have 3ppm chlorine showing but 2 parts by products and only 1 part free chlorine.

[f1steveuk]

Well the 'Anti-Algues Choc' is 20ml/m3 d'eau, as is made up of 'Dimethylamine polymerisee avec le (chloromethyl) oxirane concentrate 17.5% m/m',   well that's what it says on the bottle!!!

Long term I have Anti-Algues Super which is 'ammonium quaternaire en solution de aqueuse', that's 1/4 a litre for every 100m3 over seven days

Then I have Anti-Algues Super pastels, 200g per pastel, which will be automatically dispensed (by a neighbour!!) one every two days until they are gone. Then he has promised to check every other day while we are away.

I may go back to an inflatable paddling pool, filled up when I need to lie down!!

[Théière]

Thanks Steve. your algae choc treatment is a floc and ammonium quaternaire compound so does two jobs (Polyquat), Quaternary ammonium is not strong enough to fight algae once it's established only copper based algaecide can do this but it may help when used along side chlorine. By itself chlorine is the most efficient algaecide we have as will kill algae in around 30seconds (green) but mustard (yellow) algae is much tougher. Set your chlorinator higher and lower your ph to 7.0-7.2 and you will be boosting the chlorine killing effect by around 40%. You really need to keep it choc'd until you go home at least I would advise taking it to 20ppm chlorine and holding it there. The most powerful choc available is Calcium hypochlorite this must be dissolved in a bucket before adding as it will harm you liner if the granules sit on the liner.

Keep brushing to, this is not a spectator sport, speaking of sport I'm off to watch the pratice session to see Alonso spit out his dummy again [:)]

[f1steveuk]

Yes, I have been brushing two times a day, my other half thinks I have met a woman up by the pool!

Thanks for the help and advice.

Alonso needs taking to one side and given a stern talking to with a fist!! I think Webber should get on the front row, and win Sunday, it's his sort of track, Vettal is a bit ragged on the brakes for the point and squirt sections. I used to love working on the Hungarian GP above nearly all the others, especially as it's the track Mark (Webber) gave me a few pointers in the safety car, although he was a terrible passenger!!

[f1steveuk]

Bumping my owm thread!

Got back after the three months, have taken two weeks to get the water clear, and guess what, the brown stain is still there, in the same places and no worse, but no better. Looks like someone has scattered brown sugar into the pool and it hasn't disolved.

Hoovered, brushed etc etc, just the same as it was, weird and annoying!

[Théière]

What did you have to do to get the water clear (2 weeks??)

The info doesn't change I am afraid, need the chlorine, CYA and pH levels as a minimum.

Could the stain be under the liner? At a pool I visited earlier this year some brown stains had appeared and they had a leak too. The result was due to a small amount of water that worked under the liner and deposited some brown silt. Cleaned the carpet so to speak, et voila! no stain.

[f1steveuk]

Got the water blue very quickly, but the filter was very very dirty, so the water was cloudy, so just poor filtration, flushed the sand filter, lots of backwashes, and I suspect there was a lot of debris (flies, blossom, leaves etc) and all is fine. Levels are all ok (according to my domestic testing kit), the stain looks exactly like it did before we left 3 months ago. I felt certain it was Tanning stains, but I'm going to do a further test in a minute, then we go back to the UK Friday!!

[Théière]

Tanning, (organic) stains will bleach away with chlorine relatively easily, I just removed some from a brick wall yesterday.  Javel being heavier than water will sink to the stain if you can contain it in any way, with the pump off the water on the bottom will be pretty still. The javel will diffuse slowly into the bulk pool water so no major issues with the liner.

As we said previously the use of stabilised pool salt will increase the level of cyanuric acid (CYA) which will decrease chlorine's ability to remove the stain so you would need to run the chlorine at a higher level to over come this 2.5-3.0ppm would be quite normal for a pool with 30- 50 ppm CYA. CYA is an important part of the equation.

As you are returning to the UK at the end of the week grab a sample of your water and send it to me, i'll test it.

[f1steveuk]

Just did a "dusk" test, Chlorine very up, ph very down. I'll let you know if things change, if not I'll put a sample (the pool, not me) in a plastic test pot!