NJPools.club Community

**Posted from Bali** Oh wow, that sounds intense! First, take a deep breath - panicking won't help. Black algae is notoriously stubborn because it has deep roots in porous surfaces like gunite. I've dealt with similar issues in natural swimming ponds. The location behind your lights is problematic because it's a low-circulation area where algae thrives. **Immediate steps:** 1. Don't just shock the pool - black algae needs direct contact treatment 2. You'll need to get behind those light fixtures (turn off power first!) 3. Use a stiff brush and a specialized black algae treatment What's your current chlorine level and pH? This will help determine if your water chemistry is contributing to the problem.

**Posted after morning WOD** @LadderLord46 is right about the brush - you need to ATTACK this like it's Fran! Black algae is the CrossFit of pool problems - it won't go down easy. I had this in my pool last summer. Here's my battle plan: 1. **Power down** - kill all electricity to the pool 2. **Remove light fixtures** (might need a professional if you're not comfortable) 3. **Scrub like your pool's life depends on it** - use a stainless steel brush on the gunite 4. **Apply treatment directly** - I used a trichlor tablet rubbed right on the spots 5. **Maintain aggressive chlorine levels** for at least 72 hours This is going to be a grind. How old is your pool? Older gunite is more porous and harder to treat.

Fascinating biological event! Black algae (*Gloeocapsa magma*) isn't actually algae but cyanobacteria with a protective outer sheath. The explosion behind your lights makes perfect sense - they create warm microenvironments with limited water flow, perfect for rapid colonization. **Scientific approach:** - The sheath makes it chlorine-resistant (explains why normal shocking doesn't work) - You need to physically breach the protective layer before chemicals can work - Consider copper-based algaecides as they disrupt photosynthesis at cellular level Have you noticed any changes in your filtration recently? Reduced flow could contribute to localized blooms. Also, Florida's humidity and temperature are ideal growth conditions right now.

**Posted between meetings** Ugh, I feel your pain. Had something similar last month. As a busy professional, here's my efficient solution: **Short version:** Hire a pro. Seriously. **Long version if you insist on DIY:** 1. Schedule 3-4 hours this weekend (it will take longer than you think) 2. Buy: Stainless brush, black algae treatment, trichlor tablets, test strips 3. Remove lights (YouTube it first) 4. Scrub until your arms burn 5. Treat, wait, retreat 6. Consider adding a weekly algaecide to your maintenance routine Real talk: I wasted 8 hours over two weekends before calling someone. They fixed it in 2 hours for $300. Sometimes time = money.

**Posted from Chiang Mai** @FilterFan - Great scientific insight! The cyanobacteria explanation makes total sense. @WaveRider makes a valid point about professionals, but if you're determined to DIY: **Eco-friendly option:** After mechanical removal, try hydrogen peroxide (35% food grade, diluted). It oxidizes the cellular structure without adding more chemicals to your pool. I've used this in natural swimming systems with good results. **Prevention for the future:** - Increase circulation behind lights (maybe a professional can adjust positioning) - Weekly brushing of ALL pool surfaces, not just visible areas - Consider a UV system if this becomes recurrent Can you share a photo? The pattern might indicate whether it's spreading from one source point.

**Posted after evening metcon** Love the hustle in this thread! @WaveRider - $300 sounds like a win if it saves time. **Battle update from my experience:** The stainless brush is NON-NEGOTIABLE. Nylon won't cut it. You need to SCRAPE the roots out of the gunite pores. **Pro tip:** After brushing, use a shop vac to suck out the debris before it spreads. **Maintenance mode:** Once cleared, I added 15 minutes of extra brushing to my weekly pool routine. Prevention is easier than cure! How's the fight going, OP? Give us an update when you can. Remember: Embrace the suck!