John Faulkner
Member
Strangest thing woke up this morning and only the deep end of my pool is bright green, shallow side still looks clear. Never had algae split like that before. Any idea why it would only happen in one half?
Pool turned green only in the deep end overnight
- Thread starter John Faulkner
- Start date
Olivia Reed
Member
That kind of thing usually points to a circulation issue. The deep end tends to get less water movement, especially if your return jets are aimed too high or the main drain isn’t pulling much. When chlorine levels dip even slightly, that still water becomes the perfect spot for algae to start. Try brushing the deep end really well, shock the pool, and make sure your pump is running long enough to mix everything. You can also angle one of your returns downward for a few days to get better flow down there. Once the water starts circulating evenly, it shouldn’t happen again.
Edward Williams
Member
That usually points to a circulation issue. The deep end tends to get less water movement, especially if your return jets are aimed too high. Try brushing the deep end really well, and make sure your pump is running long enough to mix everything. You can also angle one of your returns downward for a few days to get better flow there.
Matthew Collins
Member
I’ve seen this happen when the deep end isn’t mixing with the rest of the pool very well. On a lot of setups the return jets mainly push water across the surface, so the shallow end stays well circulated but the deeper water can stay a little stagnant.
When chlorine levels dip even slightly overnight, that deeper pocket of water becomes the easiest place for algae to start. I noticed something similar in my pool where the deep end floor would get dull or slightly green first while the shallow side still looked perfect. My filter pressure and chemistry looked normal, but the water down there just wasn’t moving much.
What helped was brushing the deep end aggressively and angling one of the return jets downward for a few days to push water toward the bottom. After that the circulation improved and the color evened out again. It’s surprising how small circulation differences can create those weird “half the pool looks fine” situations.
When chlorine levels dip even slightly overnight, that deeper pocket of water becomes the easiest place for algae to start. I noticed something similar in my pool where the deep end floor would get dull or slightly green first while the shallow side still looked perfect. My filter pressure and chemistry looked normal, but the water down there just wasn’t moving much.
What helped was brushing the deep end aggressively and angling one of the return jets downward for a few days to push water toward the bottom. After that the circulation improved and the color evened out again. It’s surprising how small circulation differences can create those weird “half the pool looks fine” situations.