Fiberglass Pools

Calcium Deposits on Fibreglass Swimming Pools

calcium deposits fibreglass pools

How To Get Rid of That Grey/White Buildup Along The Waterline of Your Pool 

Calcium buildup is an unattractive white or greyish stain that gathers along a pool’s waterline caused by a chemical imbalance due to over chlorination. Pools made from porous materials like concrete are more likely to have this problem, while fibreglass pools are less susceptible. Testing and balancing the water regularly can prevent this from happening.

There are two types of calcium build-up: calcium carbonate and calcium silicate. The former is white, flaky, and easy to remove, whereas the latter is off white/grey in colour, takes longer to develop, and often also appears in the pipes of your pool. You can determine what type of calcium you are dealing with, with a few drops of hydrochloric (or muriatic) acid – a highly acidic chlorine – on the mineral build-up. Calcium carbonate will foam when exposed to the acid, while calcium silicate will not react at all. Remember to always use gloves, long pants, and eye protection when handling hydrochloric acid. 

Fibreglass Pools Calcium Deposits: Solution and Prevention

A light sanding with suitable water sandpaper should remove any calcium buildup on your fibreglass pool. As an alternative to this home solution, you can also consult a pool professional.

Chlorine reaction is continuous and needs to “breathe”. So if you have a pool cover, remove it frequently so chlorine gases can escape, preventing calcium build-up in your fibreglass pool. Another effective preventative measure is removing pool floaters ,also known as a floating chlorine dispenser or feeder that keeps the pool sanitised by releasing small amounts of chlorine at a time. It is important to use them as needed because most floaters are too aggressive with release and are not needed for everyday application.

Lastly, If you are using salt water chlorinators you shouldn’t set it to release maximum amounts of chlorine because this is seldom necessary and would most likely cause mineral build-up. Also, water temperatures that are too high encourage calcium buildup, therefore keeping a moderate temperature is important.

The most important thing is to keep a close eye on your water quality, and as a rule of thumb, the water should not smell like chlorine.

For more maintenance tips you can follow us on instagram @pools_for_africa or like our page Pools for Africa on Facebook. We provide fibreglass swimming pools in Johannesburg and Cape Town areas.