Algae from filtration problem?

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Rubywoofs

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Jun 26, 2013
12
Hello all,

I am 11 months into my first bit of pool ownership and have just joined the board today.

My problem: like many in my parts, a warm winter and rainy spring has turned my pool green. I have been working on my own, with a pool guy, and even the dreaded pool store, but it's still green. We have shocked, shocked, shocked, floc'd, green-to-cleaned, clarified, and vacuumed. When vacuuming, though, green water shoots back out of the water returns back into the pool.

My equipment: I have a 50,000 gallon pool with Sta Rite Cartridge filters. I have replaced the cartridges within the last 4 weeks.

My water returns have periodic fine bubbles. I try to purge the air from the filter housing, but just can't seem to accomplish the steady stream of water you're supposed to get to tell you the air is out. I believe I get close but get more air into the filter housing when the pump is running. The valve just seems to stop venting air or water for a while. Then, water will dribble out a little. Next day, it seems like the air starts flowing again.

So, my idea: maybe I have an air leak into the filter housing, which then causes a bubble inside the filter, which then allows water to bypass the filter media and return to the pool still green. Today, I ordered a new housing gasket and a new set up for everything associated with the air purge valve on top. Could this be my problem and my fix?

The pool guy thinks the stuff in my pool is just too small for the cartridge filter and is suggesting I replace it with a D.E. filter, but the pool was clean until 2 months ago and had been for 15 years before that (we just bought the house with the existing pool). I don't think I got the extra small algae that has never hit the pool before and didn't hit my neighbors.

Any thoughts on getting my pool swimmable this year would be appreciated.

Ruby
 
Welcome to TFP!

Algae has absolutely nothing to do with filtration. It is always a result of insufficient sanitizer.

If you maintain sufficient chlorine for your CYA, you will never have algae, even with no filter at all.
 
It does sound like you have an air leak, but an air leak would not cause anything other than air in the returns and losing prime. If you have a SWG, it is also possible that you don't have an air leak, as a SWG produces bubbles when running.

Regardless of the air leak or not, something more significant must be wrong with the filter for it to allow green murky water through into the returns. By far the most common problem is a tear in the cartridge fabric, allowing debris to bypass the filter entirely.

The pool guy thinks the stuff in my pool is just too small for the cartridge filter
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That is exceedingly unlikely. Stuff that is too small for a cartridge filter can cause hazy water, but algae, and big obvious murky green, will easily get caught by a cartridge filter.

You may also be having a chemistry issue, it is difficult to tell. You haven't said anything that tells me if you have killed all of the algae yet or not.

Anyway, focus on the filter problem first. Something is letting water bypass the filter, most likely a torn filter cartridge.
 
Thanks for the quick thoughts already.

I realize that filtration has nothing direct to do with algae, but I thought that I was likely having a problem getting and keeping my chlorine up because the gunk not filtered out was essentially depleting the chlorine. Then, as a result of not being able to maintain the chlorine, I get the algae. Am I wrong there? I do use chlorine tablets, but my water chemistry seems to be fine other than low chlorine. I have shocked the Crud out of it and 12 hours later my chlorine is still low, I use 2-3x the tablets I probably should, and my chlorine level stays low.

My pool guy meant that the particles clouding and greening my pool may be so small that they pass through my filter without being trapped. I understand there is a lower end to what the cartridge will grab, but again, my pool was clean before and I don't think anything new and unique invaded it.

I agree that a rip or similar in the filter is the most likely cause of the green water returning to the pool during vacuuming. I don't think I have a rip, though. They're new and have been re-inspected pretty thoroughly.
 
Two or three extra tablets is not even remotely like shocking the pool, even if your CYA level is low, which seems doubtful. It sounds like you need to get a full set of water test results and figure out where things really are, rather than guessing.
 
I have shocked the Crud out of it and separately I have used lots-o-tabs. I've also had the water tested numerous times by the store and used my own, probably deficient, test strips.

I have tried to kill the algae, but can't guarantee I have. It's still green - does that say it's still live? I thought the repeated heavy shocks and the separate heavy chlorination would kill the algae. Again, though, still green.
 
Did I read that right? 50,000 gallons? :shock:

There might be a filtration problem if you see stuff shooting out the returns, but the filter did not cause the green. More likely, astronomical CYA from powdered forms of chlorine have so stabilized the water that the chlorine has to get so high to kill the stuff that you never get there. I mean...50,000 gallons - you'd probably be just endlessly opening and pouring jugs of bleach in to keep the FC level up.

Let's start with some test results - and that's a grown-up sized pool, it needs a grown-up test kit - and see where to go from there.
 
Rubywoofs:

Welcome to TFP :wave:

Well, some of the Moderators and other members beat me to it, but I'll support what they're saying...

The next step in diagnosing what's going on here is to post test results!

Rubywoofs said:
We have shocked, shocked, shocked, ...
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When you were shocking, did you test FC several times a day and add enough chlorine to maintain a proper shock FC level for your pool's CYA throughout the day? During the shock process, FC is consumed at a high rate due to killing the algae. Therefore, it needs to be replenished to stay ahead of the algae.

If you don't already have one, you will need a good test kit to properly manage your pool. In fact, a good test kit is needed to properly shock a pool. Here is a comparison of the recommended Test Kits.
 

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I am lost

Merged threads. Folks need the history to respond. Let's keep it all together until your pool is cleared! :wink: Butterfly


but trying very hard. I know - get a test kit. I will, but don't have it tonight.

My pool has been green for almost 2 months. Nice and clear before that. Tried many, many things (most of which I now gather the folks here don't recommend).

My CYA, according to the pool store, was 75 a month ago. I have used lots of chlorine tablets since then. I can't get to the store for a kit or a sample test right now. Say I've used 20 3" tablets since then, is my CYA likely to be so high I'll never get the pool shocked? Like everyone else, I don't want to drain and refill my pool, but it's too green to swim in, so I'm getting no kid-splashing help.

I guess I have algae (I've put lots of shock in and recently used a copper algaecide, but it's still green). I can't really get it to hold much chlorine (according to the test strips). That all sounds like algae, right?

So, now I gather that getting my FC high enough will wipe out algae, but I need to get my CYA down some. I also gather, though, that without enough CYA and without using stabilized chlorine, I can't keep the pool chlorinated. I've read lots here, and so far it's added to my confusion rather than solved it.

I guess I'm now just asking for suggestions for my immediate next step. It's almost July and my kids haven't been in my pool. It's killing me.

Thanks in advance.

Ruby

(I posted another question earlier, and that was the beginning of my realization about just how lost I am.)
 
Yes, 50,000 gallons according to a surface area measurement x depth using an online calculator. It's big, and a big headache right now.

I will get a test kit asap and get back to everyone.

When I said I "shocked" it, I meant I have added many pounds of shock. I have not shocked it as meant by this site (just found the site today).
 
Rubywoofs said:
My CYA, according to the pool store, was 75 a month ago...Say I've used 20 3" tablets since then, is my CYA likely to be so high I'll never get the pool shocked?
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Not necessarily. Here's why: Pool Store testing is notoriously unreliable, especially for the CYA test. My experience has been that the pool store test results for CYA have always been about twice what my test results are. The lighting for the CYA test is critical and there is not enough light in the typical pool store to accurately run this test. I always run my CYA test outside at midday on a sunny day. I manage my pool according to my test results, not the pool store's. I take an occasional sample to a pool store just for grins :) However, since you have added 20 (presumably 8 oz) tabs since the CYA test, the tabs have added about 13 ppm of additional CYA.

Of course, we will not know for sure what the current CYA is until you test using a good test kit. Here's where the tough love comes in... :wink: If you are serious about getting your pool in shape the quickest way possible, you will order one of these Test Kits tonight. Your pool and your kids will thank you for it! Depending on where you are located, you should have your kit in a few days. If you order the kit tonight and then follow our advice when you get it, there is a chance that your pool could be sparkling come the Fourth of July weekend. :swim: It may take some effort, but it's not Mission Impossible.

Once you decide on a kit, here is the order page: http://tftestkits.net/Test-Kits-c4/. The TF-100 or the K-2006 can be ordered from this page.
 
I am going to back up what everyone else has said, having accurate test results is half of the key to keeping a well balanced pool, the other half is the knowledge of what to do with those test results, for that part there is the pool school link in the upper right corner of this page. We can help, but you have to be willing to put in a little work, learning how to maintain your pool, and completing the shock process, which will likely require that you dedicate some time to testing, adding chlorine (bleach), scrubbing, and testing again, clearing an algae bloom is a sustained war against algae, this means replenishing your chlorine levels as they get killed off by the algae, and not letting the algae have time to regroup and multiply. What you have done so far is over and over knock the algae part way back, then not maintained the chlorine level allowing them to multiply and a day or two later you are back to where you started from , over and over again. If using dry chlorine products and algaecides you were also likely building up lots of unwanted chemicals in your pool in the process, many of which can only be removed through water replacement (CYA, CH, Copper, etc)

Ike

p.s. You can kind of think about CYA like you should think about salt in your diet, too much is bad, too little is bad. On the one hand CYA buffers your chlorine and protects it from being burned off by the UV light from the sun, on the other hand, too much CYA buffers the chlorine so much that it is not effective at doing its primary job of sanitizing your pool and keeping the algae from getting a foot hold
 
Rubywoofs:

A time-management suggestion: While waiting on your test kit, I would advise you to stock up on plain liquid bleach. A 50,000 gallon pool going through the shock process will need lots of it. Try to buy it from a place with a high turnover such as a warehouse club (best bet), Wally World, the grocery store, or even a pool store (if the pool stores near you carry liquid chlorine). I would avoid home centers that carry liquid chlorine - it tends to be a slower moving product there. As a result, it can degrade from sitting on the shelf for extended periods of time.
 
Thanks for the suggestion, Bo. Do I need a few bottles, a truck full, . . .? Once I get my water balanced, including the appropriate level of CYA, how much 12.5% bleach should I anticipate going through in a week or month?

Thanks again for the help already.
 
That's a tough one to answer right now since chlorine will be consumed at a rapid rate during the shock process and will likely need to be replenished several times a day. I can comfortably say that it will be closer to a pickup truck load vs. just a few bottles, at least for the Shock Process. Though we do not have a handle on your pool's exact CYA yet, here's an example for a 50,000 gallon pool at a CYA of 60 ppm to give you some idea of how much bleach you will need: It will take an initial dose of about 8-10 gallons of 12.5% bleach to hit the FC target of 20-24 ppm, depending on the starting FC level. Since the chlorine needs to be replenished several time a day during the shock process, you will need supplemental doses of bleach. The rate at which chlorine is consumed is the wild card. However, each supplemental dose will be less than the initial start-up dose. Nevertheless, you will still go through several gallons a day until you pass the criteria of "done" for the Shock Process.

Once you are finished with the shock process and go into maintenance mode, you should need about a gallon or so to maintain your FC level. In maintenance mode, chlorine is still consumed daily, but at a slower pace than it is during the shock process. Therefore it still needs to be replenished daily at least during the swim season.

One thing that will help us tailor our advice... Please add the state and nearest city in which you live to your profile. Don't need the specific town - nearest major city will suffice. Your climate is important to the advice you receive. By doing this, it will appear in all your posts without you having to enter it each time. Here's how to do this: Adding location to your profile.
 

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