If I cover my low tec tank will I need more light

[Lynn]

With fall coming and colder weather I am questioning whether or not to cover my 20 gal tank.    I live in an area with hard water and high lime content which is the reason I do not have a lid on now; everything turns white very quickly.    If I cover the tank will I need to purchase a stronger light.  Right now I have a Aquarium Co-op Finnix Stingray light on it and it is very low light.

[TheDukeAnumber1]

Are you trying to grow plants, what's your goal with the light? Regardless minerals on the underside of the lid will diffuse/block some light, but you can solve this with periodic cleaning of the lid.

[Lynn]

Yes, it is a planted tank and I am afraid that the cover will block enough light that even the low light plants will have a hard time

 growing.   

[siniardem]

I have a lid and this issue but vinegar watered down cuts the mineral clean up to an easy scrub if scrub is even needed. Also my light came with the tank so there is a glass opening for it where the rest is plastic covered. I leave it on 12 hours for optimal growth. If algae starts to grow on the glass between the light and the tank where the minerals collect and splash, I will hit that part with vinegar so that between the 12 hours of light directly on the algae and the vinegar it will burn out the green growth of algae but will benefit the plant growth all year round. 

[Paul]

I have a Finnex Stingray 2 on my 120 (2’x2‘x4’) with a lid on it and have no issues growing plants. I’ve got swords, crypts, dwarf Sagittarius, java fern, Anubias and water sprite to give you an idea on what grows in that deep of a tank with that light on it. The light is on 10 hours a day. 

[TheDukeAnumber1]

@Lynn

You can run a quick test with a light meter app on a phone. I may give you a rough idea on how much light the lid will block.

[Lynn]

Thank you everyone for your help.   First planted tank.