just look down the holes with your flash light and look at the water reflection as a guide.
there are 2 plastic level indicators inside the holes pointing downward towards the top of the water.
you should see the reflection of the top of the water like (( )) if they are touching the tips of the level indicators. if the reflection is flat, then you need to add some water until you see the water touch the indicators to form the (( )) reflection.
i use a tatoo water bottle like this for precise, drip-free control.
GL
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