Is this calcium scale or possibly sand like mustard algae?

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quentin_1

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Gold Supporter
Jun 28, 2013
60
New Jersey
Hello folks,
this is my first and i look forward to learning a lot from this forum (already did by reading various threads!)
we just bought a house last fall and this is the first season of us using the pool.
information about the pool, based in New Jersey - 24000 gallons, use DE filter, i use BIOGARD products (shock, back up algae, and polysheen weekly, plus keep 3 chlorine silk sticks in skimmer)

latest test readings:
Chlorine - 10 (high so i am not adding silk sticks)
ph-7.8
tot alk - 272 (adjusted alk 224)
CYA - 160
Tot. hardness - 205
saturation - 0.5

i've had very a couple of medium size brownish spots in the deep end of the pool - they did not respond to brushing but i think they faded in color some once i shocked the pool. i kind of left them alone and perhaps i should not have. then in one area of the pool in the shallow end, i had spots forming that looked like scale, hard to the touch, sand like - also could not brush them off. these spots looked like what we've seen in biology class when you put two glass sheets together and the water and the liquids formed those "ameba" shaped forms and the like. forgive me if the description is a bit odd but i am trying to do the best to describe it.

then, i had the water tested last Tuesday by the pool store and they recommended i added Biogard balance pack 100, 25 pounds split into 3 applications. i did that and now i have these ameba-looking spots all over the floor of the pool. again, they are hard to the touch and dont brush off using a regular brush (not metal bristles).

i went to the pool store again last evening and they have recommended, based on their tests and my description, that i add 2.5 quarts of Biogard Scale Inhibitor. i did that last night. i had left the pump running overnight but this morning i see no changes.

to lower alkalikity, i also added 1lb of Biogard low n slow this morning; will do the same tomorrow morning as well - all told by the pool store of course as i am a newbie at this.

i am worried that i am not getting the right recommendation from the pool store. i've read up online, including this forum, that this could possibly be mustard algae that at times becomes sand-like vs. slimy types of algae. mustard algae seems to be able to fight chlorine so it's possible i have this type of algae despite relatively high level of chlorine in my pool (10 currently albeit there is no discomfort at all swimming). also, given my high chlorine level, i also think i've read that my other tests could be wrong so i am a bit at a loss as to what to do next.

i am hopeful i've provided sufficient information for you folks to give me some advice. please let me know what else i could provide for you to help you determine what i've got.

many thanks in advance!
 
Re: Is this calcium scale or possibly sand like mustard alga

Welcome to TFP!

With a CYA of 160ppm, your chlorine at 10ppm isn't high, it's actually a hair on the low side.

I'd recommend you read pool-school/ to get an understanding of chemistry. You are spending a lot of money on products you don't need. Your TA is already high, and you added more with the Balance Pack 100. It's just expensive baking soda, and it was the last thing you needed. You are being pool-stored.
 
Re: Is this calcium scale or possibly sand like mustard alga

thanks JohnT for your welcome! i do feel i was being pool schooled - especially last night. 70 bucks down the drain and i have not solved the problem. hence i figured i will join this community. i have perused the pool school already and have saved it to my favorites. i cant remember all of the tidbits just yet.

JohnT - any thoughts on what i should be doing right now and do you recognize the problem i am having? given that my chlorine is a tad low - should i be adding some chlorine to the pool? i use 1lb Biogard shock - how many of these should i be adding?

many thanks again!
 
Re: Is this calcium scale or possibly sand like mustard alga

Tell us more about your pool. Particularly what kind of surface.

Adding Low and Slow won't lower your TA. It will lower the pH, but the TA will bounce right back up.

Have you ever used copper products in the pool? Algaecides and alternative sanitizers often have copper in them, which can build up to the point it stains the pool surface.
 
Re: Is this calcium scale or possibly sand like mustard alga

it's a plaster pool; light blue in color (not sure if that matters). i have never used copper products. the only algaecide product i've been using is Biogard Inhibit Back Up - it has no copper in its ingredients. based on the CYA vs. FH chart and as you said, my chlorine is low so hence i think this might be the issue. you pointed out the cya vs fh misbalance. to lower cya i think i need to drain the pool.

JohnT - as you can tell i am a newbie and am not hiding that. i promise to learn and not ask the same question twice!
i am all ears as to what steps i need to take.
many thanks!
 
Re: Is this calcium scale or possibly sand like mustard alga

You very well may need to drain the pool, but as long as you can keep the water clear, you can deal with it. It sounds like you already keep a close eye on the pool, which is half the battle. A little knowledge and you'll find your pool care gets cheaper and easier.

Read through Pool School at the link in the upper right corner of the screen.

Try scrubbing the spots with a chlorine stick to see what effect it has. If it doesn't do anything, try scrubbing it with a vitamin C tablet.
 
Re: Is this calcium scale or possibly sand like mustard alga

thanks. will try your advice (chlorine stick and vit C). from what i've told you, it looks like it's hard to determine if it's calcium build up or mustard algae i guess.
 
Re: Is this calcium scale or possibly sand like mustard alga

Thanks Dave. To lower cya, my only option is draining the pool, correct? That's what the pool school says at least. How did I getmy cya so high to begin with? I want to know what I may have been doing wrong.

If it is not mustard algae, then it must be calcium build up then.

Lastly, I called Biogard customer service and spoke to 2 very nice gentlemen separately - both do not subscribe to high cya and higher FC ratio (my FC of 10 at 160 cya is lows per table in pool school). Go figure. not sure why knowledgeable people don't agree on pool chemistry!

Thanks.
 
Re: Is this calcium scale or possibly sand like mustard alga

CYA only gets in your pool when you add it...either as a separate product but, more commonly, when you use pucks or powder to chlorinate your pool.

What we teach about the FC/CYA relationship is based on rock solid science and the experience of thousands and thousands of members here on TFP.

I cannot speak for Bioguard
 

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Re: Is this calcium scale or possibly sand like mustard alga

Welcome. :wave:

If you want to take your pool back and get away from the pool store, then I highly suggest you invest in a good quality test kit that is reliable. You have 2 to chose from. #1 is the TF-100 and #2 is the K-2006. Pick one. Order it. Take Control.

Keep reading pool school and stay away from the pool store. Once you get your kit, post the numbers and we'll be here to help.

P.S. Do a partial drain/refill. That CYA is way to high.
 
Re: Is this calcium scale or possibly sand like mustard alga

Thanks again guys. I have not been adding anything other than Biogard 1lb shock and silk sticks for chlorine, nothing else. It's been raining very heavily here in new jersey so perhaps that affected cya? (I still have plenty to learn).

I will be ordering one of these test kits, for sure.

Need to find out how to drain te pool - don't know how to do it. I guess I can try to get rid of some water through backwashing. I have a drain at the bottom of the pool so I must be able to drain the water that way I assume. Should I get rid of 50% of water so I am at 80 cya?
 
Re: Is this calcium scale or possibly sand like mustard alga

I have not been adding anything other than Biogard 1lb shock and silk sticks for chlorine, nothing else. It's been raining very heavily here in new jersey so perhaps that affected cya?
Click to expand...
Rain contains no CYA but the sticks and "shock" you have been using does.
 
Re: Is this calcium scale or possibly sand like mustard alga

Here is the latest folks - what I have is plaster etching. So the stuff I could not brush off are little "etchings" in my pool plaster. I had a service done on my pump today and the technician from the pool store told me that I had a lack of calcium, most likely, and perhaps higher FC, ant those two ate away at the plaster. Kind of makes sense to me.

Does This make sense to you guys? Can these etches/rough spots on pool's plaster be touched up somehow? Also, how often does one have to redo the plaster in the pool?

Many thanks.
 
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