Green Water Overnight
16 replies to this topic
Posted 2009-12-23 08:57:36
Hi all. I cleaned the pool the other day and it was looking lovely. A lovely crystal cear blue. I got up the next day and it is murky and a green color. Did the heavy rain cause it ? or something else ? I have dosed it up with the quick dissolving chlorine tablets but don't want to over do it on the chlorine. Any ideas as to the cause and a quick way to get it back to blue. Cheers in advance Dunc
Posted 2009-12-23 10:31:43
Had a green company pool in Malaysia. Turned out the filter valve was set to recirc not filter.
I think you will have to "shock" the pool now to eliminate the green.
Posted 2009-12-23 10:38:13
First things first, test your water to see where your chlorine and pH sit at the moment. Check for stabilizer (usually cyanuric acid) as well. Before going further, the two should be at recommended levels.
If you think it's algae, and your pool gets plenty of sunlight, just pour a jug of household bleach in. The household bleach is an unstabilized form of chlorine and the sun should flash it off in about an hour. If you have a sand filter, pour some into your skimmers and let it run through the filter.
Fast algae blooms are often a sign of phosphates in your water. If you don't have a test for phosphates, have a local pool shop test for it. Phosphates can be flocced with a special sequestering agent that any decent pool shop will have in stock. Vacuum the pool (to waste, not the filter) about six hours later.
You should follow up with treatments of algaecide weekly, and if its an ongoing issue, preventative doses are a good idea.
Clean your skimmer pots daily. Dark, damp spots like this are the first places these blooms usually show up. If you have green goo inside the skimmers, you have a growing algae infestation. If it's grey, you have an infestation but your sanitizer is killing it. In either case it's a sign for you to take action to head off a much larger problem.
Posted 2009-12-23 12:19:37
Cheers CD I will try what you suggest. The PH is OK but the Chlorine level is a little high. I will get the pool company to check for the phosphates. Chers again Dunc
Posted 2009-12-23 12:38:24
Getting the green stuff out will most likely need super chlorinating.
So your "little too much" chlorine level is actually not enough.
But you'll also need to find out how it could happen. Checking for phosphates is one step of that, however a pool which has been perfect for a long time will likely not have this problem.
In my (limited) experience it often happens with the pool boy skipping a few doses of chlorine! When chlorine levels go down, the green stuff can appear really fast.
Or indeed having the 6 way valve on recirc instead of filtration.
Another possibility is the PH going wrong, low or high PH will reduce or even take away the effectiveness of the chlorine. Heavy rain could indeed cause this. Heavy sustained rain will also dilute the chlorine levels at the same time throwing a double whammy.
Posted 2009-12-24 10:31:59
This sounds very much like standard green algae and needs treating with a special algaecide. A shock chlorination will not necessarily do the trick - people tend to regard chlorine as a panacea. Using household bleach instead of special pool chlorine is dangerous, and is asking for trouble.
. poll shops sell it in 3.78 litre bottles but although it all comes from the same manufacturer, prices differ from a reasonable 900 baht to 2,200 in the greediest of pool shops.
The best way is to carry out the treatment in combination with a water clarifier, also available in the same packaging, made by the same firm, and retails in the same price range.
You may need to use two, or even three bottles, It you are being taken to the cleaners on the prices, itmay be cjeparto change your water for clean water, and start it with a prophylactic alnt algae treatment.
If the sand in your filter hasn't been changed for years it culd be harbouring all kinds of nasties, so now is the time to do it and change it for crushed silicone dioxide granules which out perform silica sand by 30 times, reduce the need for backwashing, and needs only 75% by weight.
Posted 2009-12-24 15:17:53
You are incorrect.
Household bleach is exactly the same as pool chlorine. Both are sodium hypochlorite, the household bleach is typically about 5-6%, the liquid chlorine I use in pools is 12%, which gets diluted to 6% when added to the pool's chemical storage tanks.
Here's the MSDS records for both:
Liquid pool chlorine (typical/undiluted)
Generic household bleach
Superchlorination will destroy most of the algae, and it is the least disruptive way of killing the most algae. It will also free up combined chlorine that has built up as your sanitizer fought the infestation. What's left can be treated with follow-up doses of algaecide, but be careful not to overdo it as many will mess with your pH and cause you all kinds of headaches.
One word of advice, use chlorine/bleach and superchlorinate rather than using store-bought "shock" as most of these produce ozone which is a far less effective sanitizer.
Posted 2009-12-25 09:11:52
I recently installed Pool RX & the reports so far are very positive such as "no more slimy feel on the tiles" & "have managed to cut back the pump running times". They are placed in the pump basket & give off a slow release which acts as an algaecide. Every 2 or 3 months a booster is needed but the original unit should last one year. Please note this pool also has saltwater chlorinators installed.
My understanding is that ozone is a far more effective sanitiser than chlorine but the problem is you cannot maintain a residual so effectiveness depends on how you look at it.
Posted 2010-02-24 00:54:43
Sounds like you have a ferric chloride problem. If you just cleaned the swimming pool and added new chlorine, the chlorine forces the ferric chloride to crystalline out of solution, particularly if the pool is acidic. Sunlight refracting off the ferric chloride crystals make the water appear green. The green typically appears overnight after a new batch of chlorine was added. It does not sound like algae as this forms slower, not overnight.
Ferric chloride is used in Thailand in the water treatment process. A small residue is left in the water. Often when pools are first filled they suffer this problem. Depending upon the concentration they can go brown.
In time the pool filter will remove it but it will take some time.
A quicker way is to use a flocculant which causes the ferric chloride crystals to stick together. The larger particles then sink to the pool bottom where they can be vacuumed up.
Commercial flocculants are sold in liquid form in most pool shops. One of them is "Pool Clear" at around 1500 baht for 2.5 litres. These products are a very expensive way of buying
Alum in a solution.
You can buy crystals of Alum (Aluminium Sulfate) in good hardware shops for about 25 baht a kilo. It appears as broken irregular white crystals. Buy 5 kilos. Dissolve about a two fist size lump of the white crystals in a two litres of warm water. It does not matter if they do not all dissolve. Turn off the pump. Sprinkle the the alum solution on the surface of the pool and leave overnight.
In the morning you will see a green cloud of sludge at the bottom of the pool. Very slowly vacuum this up, pumping it to waste. Do it very slowly as it is easy to disturb the sludge cloud.
If the pool is still slightly green or the sludge cloud was disturbed, repeat the process with half the alum solution. Once done check chlorine and ph levels, adjust to normal and run the filter to remove any residue.
An Alum solution is also a quick way to get you pool water crystal clear if it is cloudy from dead algae suspensions or very fine dirt etc.
Hope this helps. Alum and ferric chloride are harmless.
I did have the Thai name for Alum, if I find it I will post it.
Posted 2010-03-09 08:02:24
Hi, installation of a salt water system eliminates most algea problems straight away. In fact, one rarely needs to do anything other than to vac the pool now and then and backflush the filter. No chemicals checking, no need to bother with phosphates, algaecides, chlorine, etc. Just salt, and a little bit of stabilizer (I use cyuranic acid). With two young children who use our pool daily, I could not think about adding algeacide.
Posted 2010-03-09 08:36:19
While salt pools have much less problems with algae, they aren't immune to it as there are over 300,000 species that thrive in almost every environment from oceans to glaciers. You needn't be afraid of algaecides used sensibly though. They're no danger to your kids, except when stored unsafely.
Posted 2010-03-10 10:32:00
Here is the Thai spelling of Alum: สารส้ม It's called "Saan(rising tone) Sohm(falling tone)" and they do sell it in most hardware stores.
The price for me has been between 5-10 baht/kg just outside BKK
It comes in big white crystalline chunks that you can easily break up with a hammer into smaller or even into a powder to cast across your swimming pool surface or dissolve in water first and then add that to your pool.
Hope this helps....It's great stuff just remember to vacuum to waste not thru the filter.
Posted 2010-03-12 16:10:14
I own a pool shop in Perth and have done so for many years and I have a few things I would like to add. 99% of the time a pool goes green due to a lack of chlorine in the water. Yes pools do go green overnight especially in the warmer weather. The first thing that must be checked is the free chlorine level in the water. If it is low then superchlorination will sove the problem nearly every single time. On a few very rare occasions where the chlorine tests Ok and yet the pool is still green it may be necessary to add an algaecide as what we have found over the years is that many types of algae are becoming chlorine resistant and the use of a copper based algaecide may be necessary if chlorine alone does not fix the problem. The other possible problem is high level of phosphates in the water which is essentially algae food. This also can cause pools to go green when ALL other levels test Ok. The simplest way to treat this is with Aluminium sulphate which is a flocculant and then to vacuum the residue to waste. If it was some kind of staining such as iron or manganese then the use of Alum will also help to remove the particles from the water. If ir is algae then it will be slimy and brush off quite easily. If it is staining it will be "Stained and will not brush off easily by hand. Remember to maintain your pH in the correct range as all chemicalswill be much less effective with a high pH. Staining is almost always due to incorrect water balance. Remember with pools prevention is much cheaper than the cure. As for salt water pools eliminating the need to check your water that is just nonsense. All a chlorinator does is manufacture chlorine as the pump is running, it eliminates one aspect of pool maintenance and that is adding chlorine by hand each day. If I had a dollar for every salt water pool that has gone green this summer just from my customer base alone then I would be a rich man. There are so many variables when it comes to pool maintenance that what works for one pool will not necessarily work with the next. Some of my customers MUST add algaecides every 3 months and others never need to.
Posted 2010-05-10 17:14:53
We used to use the well water to top up our pool before with the result that 1 night of rain would cause it to go green. Have been using city water to top up for 2 years now and no more green after rain. It's something to do with the minerals (or bacteria) in the ground water.