New here - big pool, big problems!

[Gretchen]

I've been reading for a couple of weeks now to work out our problems. We've always had a good relationship with this pool for the past 10 years but this year we need some counseling!

Details:
35,000 gal. in-ground (lazy L)
vinyl liner
300 lb. sand filter
skimmer, drain, 2 inlets, 1 light
15 yrs. old

When we bought this house we went to our local pool guy. Everyone does. He immediately recommended tri-chlor and we bought it. We've had no problems, but have noticed we were going through a LOT more tabs and it had been escalating for 3 years. They had changed packaging/size/brands during this time so I thought that was it.

This year we opened to algae for the first time. We've had a hot spring and use the mesh cover, plus due to work schedules we opened late. To top it off our opening was wonked - we couldn't get the pump running for almost a week. I had been throwing in small amounts of di-chlor in the meantime to at least raise the chlorine a bit. Circulation started, water sample taken to pool guy, many $$ spent and instructions followed. 3 weeks later we have to leave for Europe (to work) and the pool is still slightly green. Left instructions for our nephew to follow... which he didn't. Upon our return we found a full-scale swamp that actually hatched dragonflies. We found our problem had gotten out of control due to a filtration problem. Changed the sand. Took MANY samples to pool guy. Spent many more $$. Took more samples in and pool guy shakes his head. We've beaten it down to slightly green, more like a milky blue, but pool guy says our water samples look fine therefore it should be clear. He then rents us a second (cartridge) filter to help clear it faster. $100.00 later we're still in the same boat.

Meantime I'd been reading the forum and when I returned the filter I purchased a Taylor test kit. Pool guy becomes somewhat aloof at this point. I also purchased bleach and borax from Wal-Mart. My initial tests after 7 containers (1.42 gal) of bleach were:

FC: 10
CC: 10
Ph: 7.6
TA: 200
CYA: 100+ (probably 120-150 range)

We gave this a wait and see and continued to maintain, brush and vacuum. No significant change. After more forum reading we decided to bite the proverbial bullet and do a partial drain. We did that on Sunday and spent most of yesterday refilling (to get water trucked in we would have to go through aloof pool guy which I'm not willing to deal with at this time). I tested and figured I'd need to add 6 containers of bleach. Did that last night. The morning reading today are:

FC: 20
CC: 20
Ph: 7.8
TA: 260
CYA: 56 (hooray!!)

The water is uniformly blue and less milky, simply a bit cloudy. For the first time this season I can see barely see the bottom of the deep end. No green tint except for a bit at the deep end which seems to be filtering out. I know from the "shock chart" that we can let the chlorine fall some and still remain at shock level, so we're probably good there. Is it time to try to take the TA down? I know I could stand to lose some of the Ph as well. What else should we do at this point?

[CarlD]

Wow!

You've done a GREAT job! What you've done is exactly right. Draining your pool and bumping FC up to 20 with a CYA in the 50-60 range (you don't really know it more than that) will clear it.

The only problem I have with lowering TA at this time is that with an FC of 20 your pH is probably lower than it looks. When you measure it, try add two drops of 0007 first--to neutralize the chlorine in the sample.

Meantime, you CAN drop your pH but given what I've said, I'd go no lower than 7.2--below 6.9 can start to damage the vinyl so be safe. This will bring the TA down some. Then aerate the water to raise the pH back up, add more acid to bring it down to 7.2, etc. This ratchets the T/A down. When TA gets down below 200, you MAY (no guarantees) see the water clear.

As a bonus, at the lower pH the chlorine is more effective.

But don't rush things--take it slow.

Also, are you backwashing everyday? You may also want to add a little DE powder via your skimmer to your sand filter to improve filtration.

Add about 1/3 cup and wait 20-30 minutes. The goal is to increase your pressure by about 1 psi. If it hasn't gone up, add another 1/3 and wait again. When it hits 1 psi, you'll know how much to add next time. Every time you backwash you can add this amount of DE. It should help.

Buy the smallest box--KMart or Walmart or even Mr. Cold Shoulder should have 10lb boxes--you won't need more as that will last you a couple of seasons.

But keep doing what you are doing. Obviously it's working!

[Spensar]

Carl,

In that case, would it be fine to keep with the shock treatment until the water clears up, then fine tune the chemical balance?

[Gretchen]

Thanks! I've brushed it and let it settle since my first post. The water quality has cleared by about 50% compared to late last night. There is no longer any greenish tint in the deep end even after brushing. I can't quite see the drain yet, but I can clearly see down the walls and into the corners of the deep end! I'll pull another test this evening and try the 0007 tip to see if I can get a better reading on the Ph/TA levels. I was afraid the chlorine was influencing these and it probably is. In the meantime since we're safely at shock level and have a cloudy day today I'll just stick with brushing - it doesn't look like I have anything to vacuum at all.

I'll take your advice to wait on the Ph/TA issue until the chlorine falls. Right now since it seems to be clearing so quickly I may not have a clarity issue. I think it's too early to tell. In the meantime I'll backwash. I haven't been doing that daily because I've been confused on the filter efficiency issue - since sand filters work better when they're slightly dirty I don't want to backwash but I've been wanting to get any filtered algae out of that sand. Our pressure hasn't gone up (normal is 18) so I've held off. The last backwash was right before we did the partial drain on Sunday. I'll now backwash daily until we're clear and try the DE. I still have one bottle of blue clarifier left but I don't think it will help (hasn't to this point!) and I don't want to put anything other than bleach, borax, baking soda and MA in the pool now that we've gone through 'detox'!

You guys are great! This is the first time we've had a problem but I'm not sorry because I found this forum and feel for the first time like we're totally in control of the pool. Thank you so much!!

[Spensar]

I'll let the great mods here handle the techy questions, but will just pipe in as a pool owner who has had to clear up the post-holiday green swamp effect a couple of times over the years.

It may take a while for the water will clear right up, longer than you may think it should. My my experience is the water is often cloudy for a while after all the green is gone and the chlorine readings look pretty darn good. I found that just keeping up the chlorine levels and waiting it out has worked, though sometimes that seems to take a couple more days than I think it should. I wouldn't get impatient and start tossing in clarifier or floc, etc. as it's just a matter of time. You are also killing a lot of organic matter, so the dead algae will accumulate in the bottom of the pool as a fine dust. Best to vacum that directly to "waste" or "drain". That will use water but is the way to get it out of the pool. I have a sand filter and a lot of the fine dead algae passes through it if I vacum it through the filter.

Hatching dragonflys is a new one though! :D

[aylad]

Wow, Gretchen, looks like you've got this one under control!! GREAT job on doing your homework!! I just wanted to clarify something, though--in the chlorine readings above, you have FC and CC being the same. I'm assuming that you mean FC and TC? (free chlorine is available to fight, combined chlorine is already engaged in the fight, and total chlorine is the combination of the two). The goal is to have FC and TC the same, with CC being zero. I suspect that was just a typo, but wanted to be sure....

Welcome to the forum!!

Janet

[Gretchen]

Hi Janet - you're right, typo! Both FC and TC were at 20 this morning. I'll test again tonight but we've had a cloudy cool(er) day so I don't expect for it to have come down too far yet. I've let it settle since brushing it this morning and decided against the vac. The water is continuing to clear and I can't see anything down there that I should vac today. Not much stirred up with the brushing. I did backwash and rinse though and it looked pretty ugly even though the pressure hadn't risen. Fortunately it looked black for the first time in the viewer and not green so we must be killing the algae in the filter too.

I went out to search for DE and couldn't find any in town. Two managers at Wal-Mart didn't even know what it was. I didn't expect much - we live in a one horse town I sometimes refer to as "Lower Crapovia" and there are very few pool owners here. Wal-Mart also doesn't carry MA so I'm still going to have to return to the aloof pool dude at some point.

Thanks again for everything. I love this place!!

[aylad]

Our Walmart started carrying a small bag of DE in the pool section for the first time this year, but I haven't seen it in stock since the beginning of the summer. Lowe's and Home Depot carry it around here.

For MA, don't know if you have a Tractor Supply Company store near you, but they're the cheapest place around here. Many hardware stores also carry it in the paint department--Lowe's and Home Depot included, although they value theirs highly :eek:

Janet

[Gretchen]

Wednesday morning - totally clear pool!! I can clearly see everything on the floor of the deep end including the screw heads in the drain. No cloudy water, no milky water, no green patches. The water is uniformly clear from shallow to deep end!

I didn't have a chance to test the water last night but did so first thing this morning. I only checked for Ph and chlorine right now because I don't want to tempt myself to mess with the TA. And I already know the CYA is in the 50-60 range.

FC: 10
TC: 10
Ph: 7.6

Since the chlorine fell so much within 24 hours I'm planning on checking again at noon and again tonight so I can monitor how much it falls overnight. I was surprised at first that the chlorine level was so much lower than yesterday morning but I'm not panicking yet - the pool is SO much clearer just through the overnight period that I'm hoping the usage will level off through today. I've looked at the CYA/chlorine chart that Watermom has on a sticky and gather that I should keep my chlorine in the 6-10 range for maintenance? I'll keep an eye on the Ph as well since I've learned from other posts that I shouldn't let that fall below 7.2.

We're going to have a stinkin' hot day here today and for the first time this season I'm planning on spending it in the pool!!!

[Spensar]

Congrats on a great job! Enjoy the day.

[aylad]

Enjoy!!!!! :D

Janet