There are a few reasons why this might be happening but we’ll start with a quick brief on how the PTLevel works.
The way that the PTLevel device works is that it measures the pressure of an air pocket created at the bottom of the liquid volume. This is done by means of our “Pressure Chamber” which is the weighted part with the black tube attached that you dropped into your tank. The supplied small diameter tube is what transports that pressure pocket to the PTLevel device where it can be measured.
The reason why your device reads low is due to an air leak between the Pressure Chamber and the PTLevel device. The way to know that the issue is an air leak is to check your trends and see if the level reading is getting lower and lower over time.
If you’ve removed the small tubing, and will be putting it back on, we highly recommend that you place silicone or gasket sealant or high tack by Permatex to all of the barbs before pushing the tubing onto them. This ensures that any nicks or cuts to the barbs are perfectly sealed.
There is one thing to note, if you were down to really low readings and your level is actually high, your small diameter tubing may have water in it. With proper function the small tubing should not have water in it and when it does fill up, your readings will become inaccurate. The best way to fix this is to replace the small tubing, which we can provide you, or to remove it and use compressed air through it to completely dry it. If you can’t dry it completely, it can still provide poor readings.