KH dropping in planted tank

[PaleoShrimp]

I have a 10 gal tank with 5 pygmy cories and blue dream shrimp (about 20 adults). I tested my water a couple weeks ago with the co op strips and my KH was 0. I did about a 40% water change at that time. I just tested my water again and it read 0 KH again. My water out of the tap reads around 80 per the strips. I’m wondering if anyone knows what might be dropping my KH?  I’m guessing the answer is to change water more frequently, but I’d love to know if there is another answer. 

[doktor zhivago]

Plants and bacteria will use carbonate in the water as a carbon source. It looks like you have shrimp in there as well and they will use carbonate to build their shells.

[Tony s]

You may be needing to supplement your gh/kh to support your shrimp. Easiest way for you to do that is get some cuttlebone and tuck a piece behind your sponge filter. Assuming your nitrates are low, then you wouldn’t need to do the water changes as often 

[Colu]

You could also add some crushed coral to raise your KH you would need 1pound of crushed coral per 10 gallons you can add it to your substrate 

[PaleoShrimp]

Would cuttlebone or crushed coral raise the ph much? My ph currently reads around 6.8-7.2 and I wouldn’t want to shock the shrimp or cories too much. 

[Tony s]

it will. but it's going to do it slowly. and it will only raise it so much. to the saturation point of the water. well within the tolerances of both animals.