Assessing the pool liner is a good way to understand the pH level of a swimming pool.
It’s not the only way but it can often provide insight into what might be wrong with the pool. As a result, you will want to be careful, if you notice the pool water is clear but the liner is green.
If the pool water is clear but the liner is green, the reason can include algaecide or ascorbic acid. To fix this issue, test the water’s pH level, add vitamin C, let it settle, and then re-test the pH level to ensure it’s between 7.2-7.6. Next, shock the pool and watch as the pool liner stain goes away.
Most people attempt to clean the pool liner to get rid of the stain first. This is not ideal and not the way to go.
You will want to address the water’s pH level first. This is how you are going to keep the pool liner from staining again.
Here are the reasons your pool water is clear but the liner is green and what to do about it.
Table of Contents
Reasons The Pool Water Is Clear But The Liner Is Green
1. Algaecide
A green pool liner can be caused by algaecide.
If you have been using algaecide to remove algae in the pool, this is going to be a direct reason you are dealing with this issue.
It is common for copper to be in the algaecide and this will stain the pool liner. You will want to take the time to read the label to see what is in the algaecide. If there was copper, this is likely the reason for the green pool liner.
The best option will be to work on getting rid of the algaecide and potentially draining the pool water.

2. Ascorbic Acid
Another reason can be ascorbic acid.
There is a fine line between how much ascorbic acid can be in a swimming pool. If there is too much ascorbic acid in the pool, it is going to lead to an assortment of issues including this one.
You will want to get rid of the ascorbic acid in the pool and this can be done with the help of vitamin C.
How To Fix Pool Water That’s Clear But The Liner Is Green
1. Test The Water’s pH Level
To remove green stains from a pool liner, you will want to know what you are dealing with first.
In general, this can be done with the help of a pH testing kit.
The pH level will be too high if there is ascorbic acid in the water. This means you are dealing with excessive ascorbic acid that has to be removed.
The same goes for algaecide if it was used recently.
2. Use Vitamin C
What is the solution to remove green stains from a pool liner?
The best option is to use vitamin C to clear the water.
If the sides and bottom are green then you will know there is something wrong with the water even when it’s clear.
Vitamin C is the best solution. You will want to get the bucket that is going to let you pour a bit into the water and then see how it settles.
3. Re-Test The Water
At this point, you are going to want to re-test the water.
The pH should be getting better and the water is already going to be clear. This does not mean the job is done but you should now be good to begin working on the rest of the pH level to get it back to normal.
Re-test the water during the process to get a better read of what is going on. This is a must.
4. Shock The Pool
This is the final step.
You are going to get rid of green stains on a pool liner by shocking the pool. This is going to help remove chemicals from the water and ensure it is stabilized.
This is a must or the pool liner is going to turn green again.
It is common for there to be too much algaecide or iron in the water. Shocking the pool is going to help regulate this problem.
Final Thoughts
These are the reasons your pool water is clear but the liner is green.
If the pool water is clear but the liner is green, this means there is an algaecide, iron, or ascorbic acid in the water. To fix the issue, test the water’s pH level, add vitamin C to the water, wait for it to settle, and then re-test the pH to get it to 7.2-7.6. Next, shock the pool to clean the pool liner.
It is common for people to want to clean the pool liner first but that is not the right strategy.
Clean the pool water and then work on the pool liner.