Pump has Low (or no) Flow
Check Filter Gauge
The filter gauge is a good indicator of the pumpís performance. If the gauge reads a lower than usual pressure, the pump is not performing well and you will want to look for a pump related problem. If the filter gauge reads higher than normal, the pump is performing well but there is an obstruction resisting the water flow back to the pool, then there is most likely a filter related problem. My filter pressure is low and I have poor flow in the pool: When you see a low pressure reading, it is a sign that the pump is performing poorly. This section covers what to look for to solve your troubles. My filter pressure is very high: High filter pressure is a sign that there is a resistance in the system that is not allowing the water coming from the pump to get back to the pool. This can be caused by misaligned valves, obstructions in the plumbing (this would be unusual) or a problem with the filter itself. A filter problem is the most likely cause of high pressure. If you believe...
CAUTION! Before doing any repairs or inspection of your pool pump make sure to turn off the power feeding the pump and lock the breaker box. If the pump starts while you are working on it it can injure you severely.
Clogged Pump Impeller A physical obstruction in the pump impeller is the most common cause of low flow. Often small items can get through the pump basket and get stuck in the pump impeller, they often cause other things to get stuck with them and soon there is a large mass of debris in the impeller that restricts the flow sharply. The solution is to access the impeller and remove the obstruction. If the pump basket is in poor condition allowing larger items through it can add to this problem so you will want to replace it. Occasionally there are other obstructions such as something stuck in the plumbing between the pool and the pump, or even misaligned suction valves. If the skimmer basket is in poor condition it can make this condition much more common and you ...
Suction Leak/Air visible under the pump lid
Everywhere between the tip of the pump impeller and the pool is under suction when the pool is in operation (the water is being pulled instead of pushed). This means that a leak will not be visible as water getting out, but will be manifested by air sucking in. When air gets in the pump moves less water meaning less water flow overall, and the bigger the air leak the lower the flow. This can even cause the pump to refuse to move water all together. Suction leaks can be difficult to identify and to locate. If you see air trapped under the pump lid that will not clear out it is possible that you have a suction leak. Locating a suction leak: Inspect the pump lid first. Pump lids will often get cracks along the seams that go unnoticed. Hold the pump lid up to the light and look through it for cracks that could be letting air in. Also inspect the gasket or o-ring that seals the pump lid, if it has cracks in it or is too flattened it can cause an air leak. It is also good practice ...