Daily dirt on bottom of pool

[ShaunK]

I need some advice from someone who may have experienced what I'm going thru.
Unground pool is a couple years old (17x33). Bought robotic Dolphin to clean. Since I opened it a week ago I've had dirt on floor of pool. Dolphin cleans it, I also use vac hose - looks good. Next morning - dirt. I have a cartridge filter. New last season. It's clean. Water tested yesterday & PH was a tad high (8) so I bought the ph lower. Some days I clean it 2x. It's maddening.
I've been running the pump 24 hrs a day since opening. Someone told me it could be environmental so yesterday I shut the pump off & let the pool sit all afternoon & overnight. This morning there was no dirt!! I turned the pump back on & 4 hrs later I went out & dirt was back. There are several wrinkles in pool liner (that's another problem for another day) & 2 of the wrinkles are in front of the 2 returns (there is no main drain) & the a lot of the dirt is in front of the returns.

 

[JohnT]

Welcome to TFP!

The most likely scenario is barely controlled algae. What are your CYA and free chlorine numbers?

 

[Texas Splash]

Also be sure to update your signature with all of your pool and equipment info. As John noted, most likely you have algae. Very common after opening. If you're taking water samples to the pool store it's not helping. Their advice is generally poor, testing not accurate, and products waaaaayyyyyy over priced.

See our Pool Care Basics for all the articles you need to know. Everything from a proper test kit to removing algae and much more.

 

[ShaunK]

Welcome to TFP!

The most likely scenario is barely controlled algae. What are your CYA and free chlorine numbers?

Thanks for your reply but if it were algae I think my test results with shutting off filter would be different

 

[Texas Splash]

if it were algae I think my test results with shutting off filter would be different

Chemical readings can vary slightly if the system has been off for a few hours. For accurate home testing, we always encourage member to ensure their system has been running for ta least 30 minutes. In general, we at TFP learn a lot from accurate water tests results even if the pump was off for a while.

Ideally, we ask for water testing from a TF-100 or Taylor K-2006C to assist members to help pinpoint potential issues. No guesswork, no waste of time, resources, or money which is not always the case at a local pool shop.

You have a new cart filter, so I doubt there's anything wrong mechanically. They get overloaded fast with organics and it blows back into the pool when the system is turned on. Happened to me. Your description sounds like algae, especially after a recent opening.

 

[duraleigh]

Thanks for your reply but if it were algae I think my test results with shutting off filter would be different

85-95% chance it's algae. We see it time and time again, especially as the temps warm up into early summer.

SLAM the pool.

In order to do that you will need one of the suggested pool water test kits. You cannot perform a SLAM without your own precise test kit.

Click on Pool Care basics in Texas Splash's post above.........it'll get you started.

 

[SMS68]

We experienced this exact issue. Clear and balanced water. Pump off, no dirt on bottom…run pump overnight and dirt deposits appear along the bottom.

We SLAM’d, vacuumed to waste, tried silt bags, tore filter apart, checked laterals, replaced and rinsed sand, changed the filter head etc. No matter what, the deposits would be back in the morning. We chased it for a couple seasons and finally gave up. The “barely controlled algae” problem never manifested into anything more than the presence of debris on the bottom in the morning.

Fast forward to this year and we had to replace our pump motor. Updated to a two speed unit. We’ve been running it on low speed since May and have ZERO deposits on the bottom. Water is clear and balanced. Truly a trouble free pool again….