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You are here: Knowledge Base > About swimming pool equipment
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Sand Filter Troubleshooting Last Updated: 08/04/2010 |
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Sand Filter troubleshooting The majority of filters we encounter in our region are of the High Rate Sand variety. These filters, while fairly reliable, do require periodic maintenance. The most common complaint is that sand or debris is returning to the pool. There are a few possibilities as to why this may occur. First and simplest is that when you finish backwashing your filter, but before you put the pool back into �Filter� mode you should �Rinse� the filter. This is an extra, small step available to you on your multiport that removes the excess debris that may be in the filter plumbing and multiport and throws it out to waste. Secondly the multiport itself may have a problem. Inside the multiport is a spoke or spider gasket that has thin ridges. Once this gasket becomes worn or old it no longer has the ability to prevent the water from passing from chamber to chamber inside the multiport. Additionally there is a spring under the multiport cover assembly that keeps tension on the gasket. Once this spring begins to loose its tension water can pass from chamber to chamber inside the multiport. Once water can pass from chamber to chamber the debris can pass as well. In time you will no longer be sending the pool water through the filter, and the debris in the pool will get thrown right back into the pool. Thirdly, inside the filter there is what is known as a bleed tube. The purpose of this tube is to take the air that gets trapped in the top of the filter and bleed it back into the pool. This is important because the air is a compressible fluid while the water that is beneath it is not. Should the air compress you can have a water hammer that can cause damage to the plumbing, pumps, filter or other connected pool equipment. This tube can crack drawing the debris or sand through it and discharging it back into the pool. Additionally, at the end of this tube is a small screen. This screen can wear and break away as it gets bounced around in the top of the filter causing the tube to be unprotected from drawing the debris or sand back to the pool. The fourth cause of sand being discharged back into the pool is because there is a failure of one of the filter laterals. These pieces are long slotted specialty plastic fittings in the bottom of your filter buried in the sand. Their job is to allow the water to pass through them but prevent the sand from passing through. Typically when you have a problem with a broken lateral you will find that you will have large quantities of sand in the pool, typically piled up under the pool return fittings. The only other and quite rare problem that may occur causing debris to be returned to the pool is channeling. This occurs when the filter sand gets rivulets through the sand that ultimately allow the water to bypass the filter sand entirely. The only solution when this occurs is to perform a sand change. When the sand is first added to the filter it is very crystalline with very defined edges. As the filter does its job those edges get worn until they become rounded off. For most residential pools this will occur every five to ten years and a change of sand becomes necessary. Sand returning to the pool is typically a very easy problem to fix, and rarely requires the sand be removed from the filter. Tags:
Swimming Pool Sand Filter, troubleshooting filter problem, Backwashing sand filter, water hammer damage, filter laterals,
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