How a pool turns green in central Mississippi
Algae spores are always in the water, carried in by wind, rain and swimmers. They only take over when chlorine drops low enough and long enough to let them bloom. In Madison County that happens fast. Water temperatures in the mid to upper 80s, direct sun that eats unstabilized chlorine, phosphate-rich runoff from fertilized lawns and a steady supply of pollen and storm debris all feed algae. A pool that would take two weeks to turn in a cooler climate can turn in four or five days here in July.
The usual triggers we see on green pool cleanup calls in Madison, MS are a pump that stopped running, a chlorinator or salt cell that quit, a vacation where nobody checked the pool, a tablet floater that ran empty, or a big storm that dropped pH and overwhelmed the sanitizer. Poor circulation is a factor almost every time, which is why we look at the equipment before we treat the water.
Green, yellow and black algae are not the same problem
Green algae is the common one. It floats free and clings lightly to surfaces, turns the water pea-soup green and responds well to shock and brushing. It is the fastest to fix.
Yellow algae, also called mustard algae, looks like pollen or sand on the walls and floor in shaded areas. It brushes off easily and comes right back. It is chlorine resistant and survives on pool toys, brushes, bathing suits and inside the filter, so treating it means shocking to a higher level, brushing aggressively, cleaning everything that has touched the water and holding elevated chlorine for several days.
Black algae is the toughest. It forms dark spots with a hard protective layer and roots into plaster and grout. It is more common in older plaster pools in Jackson, Clinton and Pearl where the surface has become rough. Treatment means scrubbing each spot with a steel brush to break the crust, applying chlorine directly to the spots and maintaining a high free chlorine level for a week or more. It rarely takes over the whole pool, but it will keep coming back until it is killed at the root.
- ■Green algae: free-floating, cloudy green water, fastest to clear
- ■Yellow (mustard) algae: powdery patches in shade, chlorine resistant, recontaminates from gear
- ■Black algae: hard dark spots rooted in plaster, needs scrubbing and sustained high chlorine
Our green-to-clean process
Step one is a full water test, because you cannot dose shock correctly without knowing where chlorine, pH and CYA are. If pH is high we bring it down to around 7.2 first so chlorine works at full strength. If cyanuric acid is very high, which is common on pools that ran on trichlor tablets for years, we may recommend a partial drain and refill before shocking; chlorine cannot keep up against 150 ppm of stabilizer no matter how much you add.
Step two is bulk debris removal and brushing. Leaves and muck come out with a leaf rake, and every surface gets brushed hard to break the algae loose so chlorine can reach it. Step three is shock. We dose liquid chlorine or cal-hypo based on the pool volume and the CYA level to reach a shock level well above normal, and we hold it there with the pump running 24 hours a day. A green pool typically needs several rounds over a few days; the water goes from green to gray-cloudy as the algae dies.
Step four is clearing the dead algae. We run the filter continuously, backwash or clean it as pressure rises, and use a flocculant to drop the dead material to the floor so it can be vacuumed to waste. Step five is rebalancing: alkalinity, pH, calcium and CYA get set to their ranges, and we test for phosphates and treat them so the pool does not slide back.
Why we do not recommend draining first
Homeowners often ask if it would be easier to drain the pool and start over. In most cases, no. Draining a plaster or fiberglass pool in the wet Mississippi soil around Madison, Flowood and Brandon risks the shell floating or cracking when groundwater pushes up under it. A vinyl liner can shrink and wrinkle within hours of being exposed. Refilling from a hose is slow, and the new water still has to be balanced.
Chemical recovery is safer and usually faster. The exception is a pool where CYA is extremely high, metals are stained into the surface or the water has been sitting for a year or more. In those cases a partial or full drain may be the right call, and we will say so after we test.
Shock dosing, filtration and the role of the filter
Shocking is not a single bag. The amount of chlorine a green pool needs depends on volume, CYA and how much organic material is in the water. A 15,000-gallon pool with high CYA and a foot of leaves on the bottom can consume many gallons of liquid chlorine over the recovery. We measure and re-dose rather than guessing, and we keep pH in the low 7s during the process so the chlorine stays in its active form.
The filter does the rest of the work. Dead algae is fine enough that a sand filter will pass some of it, so we often add a clarifier or floc on sand-filtered pools. DE filters catch it well but load up quickly and need frequent backwashing and recharge. Cartridge filters need to be pulled and hosed several times during a recovery. On every green pool cleanup in Madison, MS we tell the homeowner up front that filter cleaning is part of the job and the price.
What it costs and how long it takes
Green-to-clean recovery is priced in blocks: $300 for a 2-hour block, which covers a light to moderate green pool that still has some visibility, and $500 for a 4-hour block for a dark green or black-water pool with heavy debris. Very large pools or pools that have sat for a season may need more than one block. Chemicals are billed at cost. We quote the block after seeing the pool or a clear photo, and we do not start until you have agreed to the number.
Most pools are swimmable in three to five days. Heavily neglected pools take a week or more. Once the water is clear and balanced we recommend moving straight onto a weekly service plan so it does not happen again; we see a lot of repeat green pools from owners who fix it once and go back to the same routine.
Keeping it from coming back
After a recovery, the pool is vulnerable for a couple of weeks. Any algae that survived in the filter, behind the light niche or in the skimmer throat will try again as soon as chlorine dips. We hold free chlorine at the top of the normal range, brush on every visit, keep the pump running long hours and test phosphates again after a week. If the pool had yellow algae, everything that went in the water gets cleaned or replaced.
Long term, the fixes are the same ones that prevent it in the first place: enough run time on the pump, a working chlorinator or salt cell, CYA kept in range, phosphates kept low and someone actually testing the water every week. That is what weekly service in Madison, Ridgeland and Gluckstadt is for. Call 601-967-1717 if your pool is green now and we will get it back.
Where we work
Green Pool Cleanup & Algae Removal is available across Madison County and the Jackson metro — Madison, Ridgeland, Gluckstadt, Canton, Flora, Flowood, Brandon, Jackson, Clinton, and Pearl.
Questions we get
How much does green pool cleanup cost?+
Recovery is priced in 2-hour ($300) or 4-hour ($500) blocks depending on pool size and how far gone it is, plus chemicals at cost. Send a photo to 601-967-1717 for a quote.
How long does it take to clear a green pool?+
Most pools are clear in three to five days with the pump running continuously and follow-up visits. Black-water pools or those with very high CYA can take longer.
Should I just drain it?+
Usually not. Draining risks floating or cracking the shell in wet soil and can ruin a vinyl liner. Chemical recovery is safer for most pools. We recommend draining only when CYA or metals are extremely high.
Is it safe to swim while you are treating it?+
No. Chlorine is held far above normal levels during shock treatment. We tell you exactly when it has dropped back into a safe range.
Why does yellow algae keep coming back?+
Mustard algae is chlorine resistant and lives on toys, floats, brushes and inside the filter. Clearing it means a higher shock level, aggressive brushing and cleaning or replacing everything that has been in the pool.
Do you serve areas outside Madison?+
Yes. We handle green pool cleanups across Ridgeland, Gluckstadt, Canton, Flora, Flowood, Brandon, Jackson, Clinton and Pearl.
My pool turned green overnight. How does that happen?+
It was on the edge for days. Chlorine slid to zero, a hot night with no sun let it bloom, and you saw it at breakfast. Algae doubles every few hours at 85 degrees.
Why does my pool keep turning green even after I shock it?+
Usually not the chlorine, the stabilizer. Years of tabs pushed CYA so high the chlorine cannot keep up, so you shock, it clears, it turns again. The other cause is a filter that never removes the dead algae, which becomes food for new algae. Fix the CYA, clean the filter after every shock, and hold chlorine for a week, not a day.
What happens if I just leave it green until fall?+
Black algae roots into plaster, liners stain permanently, the pump runs dry when the skimmer clogs, and mosquitoes breed. A $300 fix becomes a $2,000 one by fall.
The water is cloudy but not green. Can the kids still swim?+
Cloudy means the filter is behind and chlorine is low. If you cannot see the drain, you cannot see a kid on the bottom. Fix the water, run the pump 24 hours, then swim.