Ca too low / high

Calcium is an essential immobile plant nutrient and must be supplied by tap water, fertilizer or substrate. Generally plants take only as much as they need and not more for later use. Interestingly enough, Ca is not supplied as NO3 and PO4 by fish waste and plant decay.

FAQ

What happens if there is Ca deficiency?

Plants slow down grow rate and develop smaller size crippled and pale new leaves. Then plant becomes brittle and melts away.

What is the usual water column Ca level?

See Plant requirements

What is the lowest Ca levels I can have with plants?

Ca levels in fully planted aquariums can drop to 20 ppm.

How can I increase Ca levels?

Please see RO Reverse Osmosis

How much of Ca fully planted aquarium needs?

Very little, daily about 0.3 - 0.4 ppm a day.

I have heard about much higher Ca levels?

Some tap water comes with higher Ca levels naturally. Unfortunately high KH follows and most plants and fish don’t do well in high KH water.

What happens if there is Ca excess?

Some plants and fish don’t mind relatively high levels but some do, it does depend on particular specie.

Can fish die from high Ca levels?

Some soft water fish can.

How can I lower Ca levels?

Check fertilizer. Check water supply for Ca excess. Check decorations, rocks and substrate. Switch from tap to RO Reverse Osmosis filter.