Mustard Algae - which pool chemical levels are important?

[eebuckeye]

I have had a pool for a few years now and always battle mustard algae which is extremely annoying. Recently I used Yellow Out with a bunch of chlorine and it worked for a few weeks, however, it is back. I even used algae preventer weekly after it was gone this last time.

My pool guy tells me that algae can not really grow when the chlorine levels are high, therefore I have been keeping my chlorine levels quite high (when measured with test strips).

Is the chlorine level the only important reading to help prevent algae? For example, can mustard algae grow if the PH is too low, etc??

Thank you - I really want to understand how to prevent it!

 

[linen]

Re: Mustard Algae - which pool chemical levels are importan

Welcome to tfp, eebuckeye

Are you certain it is mustard algae?
Does it primarily grow on the shaded portions of the pool only?

Regardless, when you have algae, the best way to get rid of it is the SLAM process. See this pool school article: http://www.troublefreepool.com/pool-school/shocking_your_pool

Once you finish the SLAM process and if you have Mustard Algae, then you would want to follow this pool school article: http://www.troublefreepool.com/pool-school/mustard_algae

Test strip values are usually not accurate enough for proper pool mainentance. I would suggest before anything else, you get an appropriate test kit. See: http://www.troublefreepool.com/pool-school/pool_test_kit_comparison

Is the chlorine level the only important reading to help prevent algae? For example, can mustard algae grow if the PH is too low, etc??

Chlorine is what kills algae, though keeping you ph down around 7.2 when starting the SLAM process may marginally help. What is your ph?

 

[RobbieH]

Re: Mustard Algae - which pool chemical levels are importan

Note that the FC level required to keep algae in check is dependent on your CYA level. This is something the pool guys fail to recognize quite often. So if you've been using trichlor tablets and your CYA is over 100, it's quite likely your chlorine level is not high enough. Please post a complete set of accurate test results.

 

[eebuckeye]

Re: Mustard Algae - which pool chemical levels are importan

I'm pretty sure it is mustard algae... seems turn to dust when brushed. One thing to mention is that our pool does not get a bunch of sun (especially this time of year). Usually just 6 hours but mainly morning sun.

I used the test strips before treating the water yesterday and the levels were around:

TH: 250
TC: 5
FC: 10
pH: 6.4
TA: 40
Cya: 10-30

I have been keeping TC and FC high to help avoid the algae but it does not seem to matter. I added chemicals to the pool and remeasured today and the levels are:

TH: 250
TC: 5
FC: 10
pH: 7.2
TA: 80
Cya: 30-50

It is hard for me to judge the numbers perfectly because I am using test strips (not sure if another kit makes it easier to read).

Our Cya never gets above 30-50 so I do not think that is the problem and I keep the TC and FC high.

 

[RobbieH]

Re: Mustard Algae - which pool chemical levels are importan

Either the full TF-100 kit or just the FAS-DPD single item is what you need. You can get it from tftestkits.net. If you are measuring CYA from a strip, you'll either need the TF-100 or that single item for CYA too. Quite honestly though, I recommend getting the whole kit and ditching the strips, they just are not accurate enough.

It isn't possible to have a TC of 5 and an FC of 10. TC=FC+CC. So as you can see, there's no way the TC can be lower than the FC.

 

[Donldson]

Re: Mustard Algae - which pool chemical levels are importan

I have been keeping TC and FC high to help avoid the algae but it does not seem to matter.

I believe that is entirely because of the test strips. Your FC could be lower, or higher, who knows? As has been mentioned, FC + CC = TC. Therefore FC can never be higher than the TC. Also CYA doesn't fluctuate like the strips are telling you, it should always remain roughly the same from one day to the next if you aren't adding more. If you are reading it right, then the test strips are really very much junk and you are working blind.

I think the most important step for you to eliminate this algae is the TF-100. The FAS-DPD test doesn't involve matching colors, count drops and it gives you an accurate FC and CC reading. Very worth having!

 

[eebuckeye]

Re: Mustard Algae - which pool chemical levels are importan

Thank you for the responses! I will definitely get a 'real' test kit.

Is it true that the only levels that really allow algae is when clorine is too low (or with high chlorine and high cya)?

 

[RobbieH]

Re: Mustard Algae - which pool chemical levels are importan

Only when chlorine is too low in relation to your CYA level. That is correct. If there is chlorine in the pool at the proper level, it is rare to have any algae problems. I do get some black algae occasionally at the tile line where the water line is, but that's due to my robot not adequately brushing and me not being home to brush.

 

[eebuckeye]

Re: Mustard Algae - which pool chemical levels are importan

I just have no idea how I get algae!?! I always keep the chlorine levels higher than normal (I know it is the test strips but it is very easy to tell the levels are quite high). Argh!?! The pool is shaded quite a bit but not sure if that matters.

 

[techguy]

Re: Mustard Algae - which pool chemical levels are importan

I just have no idea how I get algae!?! I always keep the chlorine levels higher than normal

High chlorine (FC) is relative to your CYA (conditioner/stabilizer) value.

If your pool had no CYA (very unlikely except after 100% refill) high chlorine is about 3PPM

If your pool has 40CYA, the lowest you want your chlorine is 3PPM and your daily target is normally 5-6PPM

If your pool is 100CYA or more, you need at LEAST 7 PPM FC and algae will grow rapidly at 3PPM.

 

[RobbieH]

Re: Mustard Algae - which pool chemical levels are importan

I'm not trusting your test results right now, some of them don't make sense. Something isn't right, and until you have an accurate set of test numbers, it's hard to tell where the problem is.

If you have those numbers reversed, if TC is 10 and FC is 5, you have organics in the pool, probably algae.

 

[Donldson]

Re: Mustard Algae - which pool chemical levels are importan

I know it is the test strips but it is very easy to tell the levels are quite high

Could you elaborate on this? What makes it very easy to tell the levels are high?

 

[techguy]

Re: Mustard Algae - which pool chemical levels are importan

Not being able to trust your test strips is critical. Most test strips I know have ranges.

If they were a speedometer, they are like 0-5MPH, 5-10MPH, 10-30MPH, 30-50 MPH and 50+MPH (100 MPH?) If were driving in a 30MPH zone and had a cop on your tail, would you like to know if you are going somewhere from 10-50 MPH, based on the color strip because you can't tell if it says box 1 or 2 on you speedometer test strip?

 

[eebuckeye]

Re: Mustard Algae - which pool chemical levels are importan

The colors on the test strips indicate the highest level of chlorine (numberwise on the color chart). I always keep the levels there to be 'sure' the chlorine is high to fight algae.

 

[Bama Rambler]

Re: Mustard Algae - which pool chemical levels are importan

Do the strips read free chlorine or total chlorine? Most read total. If that's the case you could be reading high chlorine, but all or part of it could be CC's and your FC could be zero or very low.

 

[eebuckeye]

Re: Mustard Algae - which pool chemical levels are importan

The strips read total and free which are always at the top of the scale (10). CYA is always low to ok.

 

[Bama Rambler]

Re: Mustard Algae - which pool chemical levels are importan

Have you actually ordered the good test kit yet? If you haven't you're just spinning your wheels and you're never going to know what's going on.

 

[eebuckeye]

Re: Mustard Algae - which pool chemical levels are importan

I understand.. time to order a test kit.. I am thinking of waiting till next spring to order the kit though since we are going to close the pool very soon this year and the chemicals do seem to expire.