API test kit start from pale blue, and will turn orange, depending on the KH. If the KH is low, then you may finish with very very pale orange.
It means your water is probably 1 dKH°. Mine is 2dKH° and is a bit hard to read too...
If I test RODI water, then it start from transparent/light yellow to darker orange... It means the KH is 0 dKH°
I suggest you add a bit baking soda to new replacement water as it seems really really soft. PH flukes are bad for fishs... KH is a PH buffer that prevent flukes and raise PH a bit. Half a teaspoon of baking soda for 4-6 gallons new water is almost enough, depend on the final KH you want to reach.
If you want to test your test kit, take a 4-10g bucket, full it with water, add a teaspoon of baking soda to it, stirr, then test it. You'll get higer KH reading, and you'll be able to see the color change.