I Can't Get All The Algae Out!by David
1) My pool chemistry is balanced (chlorine, pH, conditioner, alkalinity) and has been for over a month since I opened the pool. 2) I use a cartridge filter system and inserted a new cartridge at the beginning of the season (May). 3) I add a clarifier once a week to drop the solids to the bottom and make them more likely to be filtered out. 4) I vacuum about once a week and brush about once every other day. Problem: Even after I vacuum, by the next day, there is algae on the bottom of the pool. When I push the brush along the bottom, there is a green cloud that is pushed up. I have increased my chlorine level to about 5 to 6 ppm and shocked the pool more frequently. So what I don't understand is why I still have algae in my pool even though I clean it thoroughly and the chlorine is at an effective level? What should I try next? Thanks for the question David I'd like to have your complete chemical readings: Chlorine, CYA (cyanuric acid/stabilizer), pH, Alkalinity, Calcium Hardness, and Metals (iron and copper). It makes troubleshooting much easier and the process of clearing up your pool will go much faster. You can get this done at your local pool store or use a good test kit yourself. I'd encourage you to get a Taylor FAS-DPD K-2006 pool test kit. Pool Water Testing Water Testing Kit Next is to watch the clarifier use. I never used a clarifier either for the YMCA salt pool or when I had my pool route in Arizona. If the chemicals are balanced, especially with a cartridge filter, which is my personal favorite, there's no need for a clarifier. Your algae problem could be a couple of things. Either too high or too low CYA (stabilizer) or too high pH. Anything over 8.0ppm and you're only using about 25% of the available chlorine. Add to that the wrong CYA level and you're way behind. Even if the chlorine level is 5 - 6ppm, if either or both of the above is off, you're going to be playing catch up all the time with the algae. Shocking when you have algae is a process, not an event. The chlorine level needs to stay above 12ppm for a period of time to kill the algae. Shock in the evening then retest in the morning (before the sun has a chance to hit the pool) and see how much the level has dropped. If it drops more than 1.0ppm, you still have an algae problem. Get me the actual chemical numbers and I'm sure I can help. Robert Comment: Pool Chemical Readings By: David Date: August 9, 2011 Sorry for the delay, but I have my chemical levels. Over the weekend, I added two packets of powdered Cl. The particles on the bottom of the pool still look green, also when I brush it. I went to two different pool stores, with slightly different results. Both samples were from the same area of the pool (deep end), same time of day, on the same day. Pool is ~25K gallons, 18'x36', with a vinyl liner. Water tempurature is averaging about 76 degrees Farenheit. One store recommended adding another packet of shock while the other told me that I need to add more stabilizer (CYA). Tell me what you think. Pool Store #1: Free Cl: 5.0 ppm Total Cl: Not Run pH: 7.9 Hardness: 210 ppm Alkalinity (w/stabilizer correction): 85 ppm Cyanuric Acid: 33 ppm Copper: 0 ppm Iron: 0 ppm Total Dissolved Solids: Not Run Pool Store #2: Free Cl: 5.0 Total Cl: Not Run pH: 7..6 Alkalinity: 100 ppm Cyanuric Acid: 60 ppm Hardness: 220 ppm Total Dissolved Solids: 2450 Copper/Iron: 0 ppm Phosphates: <100 ppm The fact is that I will be closing this pool around Labor Day, so all of this might be slightly moot; however, I still value your advice and evaluation which I will utilize next spring when I reopen. Thanks! David Comment By Robert Date: August 9, 2011 Thanks for the readings David. It makes life so much easier for me. We'll go from the top to the bottom with the readings. Even is your chlorine is at 5ppm, you can still have any algae bloom because it's the consistency of the chlorination that kills the algae. I would suggest getting the pH down to 7.2ppm. Chlorine works better at a slightly lower pH. For a 25,000 gallon pool, you would use 1 qt. of acid. Get a 5 gallon bucket filled with pool water and then add the acid. Stir with a PVC pipe or stick and broadcast it around the perimeter of the pool. Sweep the sides and bottom to break up any hot spots. Keep the filter running 24/7. Hardness is fine. Next year go light on the hardness if you can, maybe 150ppm. It's not that important with vinyl pools. If your fill water is already hard there's really nothing you can do about it, but don't add any calcium to the pool. Alkalinity is fine, between 80 - 100ppm. No baking soda, alkalinity or pH up. CYA is fine. Normal range is between 30 - 50ppm, but you're fine with 60. The total dissolved solids (TDS) are a bit high. 1500ppm is really the max. you want to go. The only way to reduce them is to do a partial drain and refill. And the phosphates...don't even worry about them. Here's a good post about that. Be sure to read the visitor's comments as well: High Phosphates Over 1000 & Cloudy Water Next is to shock the pool with liquid chlorine. Do this about 2 hours after you adjust the pH. Don't shock with regular chlorine granules. It has a pH of 12. If you shock with granules the pool pH will go through the roof and you'll be adding hardness to the pool. For 25,000 gallons, 4 gallons with bring the chlorine level up to 10ppm. Use 4 1/2. It's better to go a little over than under. Again, get your 5 gallon bucket filled 1/2 with water and then slowly add the chlorine and stir. Broadcast around the perimeter of the pool. Sweep the sides and bottom to break up any hot spots of chlorine. You'll want to get the chlorine level up to 12 - 15ppm. Shock in the evening, then retest the chlorine and CYA in the morning. You'll see how much chlorine has been used through the night. During this process you can use a PolyQuat 60 algaecide as an added backup against any algae blooms that might occur. The trick in clearing up your pool is to get the pH in line and keeping the chlorine level above 12ppm for a period of time. That's why you shock in the evening, retest in the morning, then shock again. Be sure to clean the filters every day. Get new ones and swap them out with the old ones. Clean them, and swap them out. Remember to test morning and evening and keep the chlorine level at 12ppm or above as best you can. You may need to do this for a few days. When the pool turns a white/gray color and you only lose 1 - 2ppm of chlorine through the night you'll know the algae is dead. If the chlorine loss is more you probably still have some residual algae. Let the filter do its job. And keep the cartridges clean. If you have a pool store that's close, take a sample of water to be tested after every turnover of the water. This is normally about 8 hours. Morning and night. They should do it for free. If you're going to be closing the pool in a few weeks, don't worry about the TDS, but in the Spring it would be good to do a 2/3 drain and refill. Do this first before putting any chemicals in the pool. If you balance everything out it will be destroyed when you add the fresh water. More time and money wasted. Remember, after you refill with fresh water in the Spring the CYA will bottom out. This is the way you reduce the CYA. Shock with Dichlor. This is a stabilized chlorine and will get the CYA in the pool quickly. Be careful when using Dichlor as it can get out of hand quickly. For every 10ppm of chlorine added with Dichlor, you'll raise the CYA by 9ppm. Once you reach the 30 - 50ppm mark, switch to liquid chlorine for weekly maintenance. Hope this helps and have a great rest of the Summer. Let me know how it turns out for you. Robert Click here to read or post comments. |
