Black Algae

[ICRC]

So for the last 2 weeks I have been battling Black algae. It started with a green pool, we shocked it and it got clear then a week later started to turn green again. Pool is very ward we live in AZ. Then we got it clear again only to see black algaue on the bottom of the deep end. Pool is very large (dont know size but built in 85) Plaster pool with spa on side. Not a regular size and about 8-9 feet deep.

Anyway pool guy gave me a box of shock and some blue chemical for black algae.I put it in right after scrubing the pool with a steel brush. Then the next day scrubbed the areas again. I checked ph and its 7.4 and checked and there is still 3 pucks in the floating container.Oh I remove the filters every 2 days and hose them off. So whats next?

Please help, will I need to drain pool?

[AFiremanFirst]

take a chlorine puck (tri-chlor: chlorine tab) and with a pair of goggles dive to the stain and scrub! Or waste money on algacides that will be ineffective!

[ICRC]

take a chlorine puck (tri-chlor: chlorine tab) and with a pair of goggles dive to the stain and scrub! Or waste money on algacides that will be ineffective!

I thought about doing that but the wife didnt think it was safe to get in the water with all the chemicals. I'm gonna need a very long snorkel!!!!

[AFiremanFirst]

the chemicals won't bother you enough to matter, must be a newly wedded, my wife throughs me in the pool when i add chemicals

[USMC_Wifey_1345]

To get rid of black algae, algaecides typically do not work, mainly just a waste of money. First way is to spread either cal hypo or granular triclor directly on the algae. Lower Ph so the killing form of chlorine is more effective generally 7.0 to 7.4. You first should brush the spots with a ss brush. Do not do this on a dark plaster or vinel liner pool, chlorine will either bleach or stain color. When doing this turn off pool sweep for a few days.

[AFiremanFirst]

good advice from USMC. I would encourage you to use a tri-chlor granular rather than a cal hypo, but it may work. to make it easy on your self, put the chlorine in a white sock and zip tie it closed. Then you can move it around with your pole and brush. Yes it may deslove the sock!

[ICRC]

Ok all

so I have used your advice and appreciate all of it but here is the problem. Today the entire deep end now has black algae!!! I have found a pool guy who says he can drain it acid wash it bleech it all for $400.00. Its either this or getting scuba gear and spend hours under water trying to scrub it.

Do you all think this is the way to go?,and a good price?

[chem geek]

Are you sure it's black algae? That usually takes a long time to grow and spread, unlike most other forms of algae. Given how quickly this has come on, especially after shocking the pool (which raised the pH), perhaps what you are seeing is metal staining -- probably copper if it's black (copper staining can be light blue to green to black, depending on the specific copper compound that precipitates; could be iron as well though that's usually a rust color though can be dark brown or even black under unusual conditions).

See this image and this image for examples of black algae and notice how it is uneven. Also, if you were to scrape off some and wipe it onto white paper, you will notice that it is really dark green. You can see copper stains here and here which can seem similar, though you can notice how the water has a greenish cast though the walls have some dark staining.

If it's metal staining, then lowering the pH (say, to 7.2 or even 7.0) and adding a good metal sequestrant should clear it up though it can be difficult -- fresh stains are easier to remove than older stains. Some metal sequestrant products (especially for iron treatments) also have ascorbic acid or other reducing agents that will require lower chlorine levels (since they will remove chlorine anyway) and will lower the pH so if you use that then you don't need to lower the pH as much initially -- just follow instructions on the particular product you use.

I suspect that in fighting the initial algae you used an algicide that had copper in it which is generally a no-no since that can produce staining.

[Pool Raider]

Not sure if you are familiar with PoolRx My link we use these, an industry alliance told me the Rx works wonders in removing black algae.

I also like Silvertrine for this as well, good luck. Make sure your chemistry is balanced before either application for best results.

Good luck

[chem geek]

PoolRx is metal ions: copper, silver and zinc. Metal ions can stain pool surfaces if there concentration gets too high or the pH rises too much. They are not necessary for preventing algae growth. Maintaining an appropriate Free Chlorine (FC) level relative to the Cyanuric Acid (CYA) level will kill algae faster than it can reproduce.

[ICRC]

PoolRx is metal ions: copper, silver and zinc. Metal ions can stain pool surfaces if there concentration gets too high or the pH rises too much. They are not necessary for preventing algae growth. Maintaining an appropriate Free Chlorine (FC) level relative to the Cyanuric Acid (CYA) level will kill algae faster than it can reproduce.

just wanted to thank all that replied. Turns it it was black algae and very bad but was sooo lucky to run into a friend of a friend this past weekend. He was short on cash and was going to vegas Friday so needless to say he drained acid washed and bleeched the pool and spa and super cleaned the filters for $300.00 total. He is also coming by Thursday to make sure all levels are perfect.

so thanks again guys it was your help that got me on the right path.

[ICRC]

NEW ISSUES

I need all of your advice.

So i had pool drained paid for acid wash and bleech refilled pool again and had no problems for a few weeks now green algae is coming back again.

My question to all of you is who is responsible for it?

Is it the pool guy that I paid$300 bucks to come back or is it the owner because washing and bleeching is not a guarentee.

Part of me wants to call him and B!tch but if its not his responsibility then I wont.

[waterbear]

NEW ISSUES

I need all of your advice.

So i had pool drained paid for acid wash and bleech refilled pool again and had no problems for a few weeks now green algae is coming back again.

My question to all of you is who is responsible for it?

Is it the pool guy that I paid$300 bucks to come back or is it the owner because washing and bleeching is not a guarentee.

Part of me wants to call him and B!tch but if its not his responsibility then I wont.

I would have to say that if the algae appeared after three weeks it is your fault for not maintaining your water chemistry. Have you been testing your FC level? Have you made sure there was enough CYA to prevent the chlorine from burning off in the sun?

Black algae only starts when the water is not being properly maintained and takes a while of bad water conditions before it appears, so this gives support that you do not properly maintain your pool or test your water. If you did you would not have gotten black algae in the first place. Since you mentioned using pucks in a floater I suspect that your pool was overstabilized. Have you ever tested the CYA levels in the pool? Sorry if this sounds harsh but it's the truth.

You need to start testing your water regularly (I suggest you get a Taylor K-2006 test kit, it is the best one for the tests you need to do) and use it weekly (daily for the chlorine and pH tests) so you can adjust your water balance and keep it in line. Once you learn your pool then you can test less often.

[Lostcauzz]

I have been working on a few commercial pools with black algae for the past few months. It is the classic example of why the 3 "tions" are needed. (circulation, filtration, and sterilization) To get rid of stubborn black algae I have been diving, with a chlorine puck and a "dental" pick (do not dig just scrape),and a strong bristle scrubbing brush. Use in this order

1. rough rub with chlorine tab (this weakens the protective barrier)

2. scrape with pick (only remove what is on the surface, and only use the pick to poke in holes where you cant scrape)

3. firmly brush

4. push hard scrape with chlorine tab. (this forces chlorine into the roots)

Here is what I have found that has worked so far to help control black algae. Sorry this is long and not simple....

lack of circulation. This allows the black algae strand to "root" itself without the threat of washing away, and creates a significantly lower chemical spread at the deep end.

common problems:

water returns all facing up or sideways

solution:

turn sidewall returns at a downward angle to increase deeper water circulation.

Problem:

not enough water pressure in returns to make it to the bottom of the pool

Solution:

A booster pump fed "robotic" cleaner will distribute more circulation on the bottom of the pool (not inexpensive)

Problem:

"robotic" cleaner not running long enough to be effective (many will set the cleaner to run just long enough to clean average debris)

Solution:

change timer tabs to allow the cleaner to run longer (possibly 1 hour after pool pump turns on and 1 hour before pool pump turns off)

Problem:

no pressure from bottom returns

Solution:

Equalize bottom returns by closing the working returns and forcing water to the non working returns (requires extensive time on the bottom of the pool) Once the returns all work, only open them back up enough to feel water flow 360 degrees around the return. (weak water pressure is better than none)

Once again, these are just my findings and are NOT the only causes and solutions to this problem

[chem geek]

Circulation is certainly important because it ensures that a consistent level of sanitizer is evenly distributed throughout the pool. However, many pools develop algae (not just black algae) because the Free Chlorine (FC) level is too low relative to the Cyanuric Acid (CYA) level and this most often occurs from continued use of stabilized chlorine (usually Trichlor pucks/tabs). An understanding of the FC/CYA relationship is important if one wants to prevent algae growth using chlorine alone.

Thanks for the tips on circulation. It is certainly one critical part of properly maintaining a pool.