Short Cycling

[donjoarm]

My pool is green and I am having a heck of a time with my filtration. I have a DE filter which will work fine for an hour (after backwashing) and then the pressure will rise and flow will virually stop. I have cleaned the filter with a commercial product and soap and water, nothing seems to work. The local pool store tells me there is nothing to add to the water to correct the algae until I have proper filtration.

This has been going on for two weeks. I am at the end of my rope. Any thoughts?

Thanks.

[duraleigh]

Hi, I'm surprised no one has responded yet. Didn't mean to overlook you.:)

Kill the agae FIRST. Running your pump and filter will clean up the dead algae and pool but you've got to get it dead before you can filter it out. Your pool store guy misspoke or he misunderstood your situation.

If you don't know how to get rid of the algae, there's a ton of info on this forum to read and get started.

The very first thing, if you want specific advice, is you must get a test kit and tell the forum:

Pool size (in gallons)
Pool type (vinyl or cement..inground or above ground)

FC
CC
TC
CH
pH
Alk
CYA

If you don't know what those are, post back and tell us and we'll get you the info.

Again, you must start killing the algae now or you'll never get out of your cycle.

Dave S.

[donjoarm]

I have a 20,000 gallon in-ground vinyl pool. I do not have the specific readings but the pool store stated that everything is in line with proper water balancing. I will have to take another sample and post the readings you requested.

In the mean time, what can I do now to start eliminating the algae without a properly operating filter?

[fog80]

are you using the bump handle after every few hours? My DE filter usually starts getting a high pressure reading every few hours when dealing with green algae. I then have to bump it and restart it for the pressure to temporarily go down.

Once most of the algae is gone, I backwash and fill the filter with fresh DE.

[donjoarm]

I have a Hayward DE 3620. I don't think it has a bump handle, it has a side monted multiport valve.

Would vacuuming to waste be beneficial?

[duraleigh]

In the mean time, what can I do now to start eliminating the algae without a properly operating filter?

"Don",

First, I am not a DE filter guy...I have sand. My assumption is your filter is working fine.....it's simply getting plugged up with algae.

Even if my assumption is incorrect, you have a green pool and Cl is the best cure.....lot's of it.

Without you posting those numbers, this is a little bit of a guess, but a pretty safe one. Put in 4 gallons of 6% clorox bleach all at once in the late evening. That will bring your 20k pool to 12ppm of Clorox and start whacking that algae. Now you need to keep it at 12ppm 'til your water clears and the only way you can do that is to test your water.

That'll give you a 24 hour head start but before we get too detailed on what to do next you'll need to help us by posting those tests.

Meantime, your pump should be running continuously....that'll help you filter out the dead algae and start clearing your pool.

Others will be along soon to advise you on your filter but it sounds like it's okay.

vacuuming to waste will not be helpful.

Dave S.

[donjoarm]

OK, I've got some numbers. I added 4 gallons of bleach last night.

FC .5
TC .5
ph 7.2
CH 200
Alk 70
CYA 100

I also have another problem-Air in the pump housing. I am trying to track down the source of that problem!

[PoolDoc]

I have a DE filter which will work fine for an hour (after backwashing) and then the pressure will rise and flow will virually stop. I have cleaned the filter with a commercial product and soap and water, nothing seems to work. The local pool store tells me there is nothing to add to the water to correct the algae until I have proper filtration.

Your pool store is full of it! Live algae plugs DE filters.

I'll never forget a night spent at a Girl Scout camp about 20 yrs ago -- they were my very first commercial pool customer, and it was my very first season, and the first and LAST time I ever let a customer pool turn green during the pool season.:o I got the call about 9pm, and was there from about 10:30 till 5am. They had a huge open pit vacuum DE filter that was BELOW water level. Every time the filter plugged, the water would overflow into the drain pit. :eek: The camp ranger and I were cleaning the filter every 20 - 30 minutes, all night long!

Kill the algae, and then filter it out. If you can, put your filter on recirculate. If you can't, turn it off, and add bleach till you kill the algae. Don't use other forms of chlorine, since you don't want it just resting on the bottom. On that GS Camp pool, it took 75 ppm of chlorine to finally terminate that algae. You can't go that high with vinyl, though.

With a 20K pool, you probably need to think in terms of 15ppm doses, though. That's around 6 gallons of household bleach per dose. Dose in the evening, and repeat everytime you find levels below 3 ppm. It may take many repeated doses, depending on how much algae is actually in the pool. Test with an cheap OTO kit (turns yellow from chlorine); DPD (not DPD-FAS) can bleach out, and cause you to think you have no chlorine, when it's really very high.

You'll probably get better results with low pH (~7.2) than with high pH (> 7.6) . . . UNLESS you had high CYA when you closed the pool, and now have low CYA. (Test to find out!). In that case, you'll need to RAISE the pH to around 8.0 with borax before you began dosing with chlorine. You'll get very fast algae kill, in that case, but you'll have to continue adding chlorine long after the water is clear, to get rid of all the chemical residue from bio-degraded CYA.

Do NOT mix in other algaecides. Adding copper when the chlorine is that high, will only result in stains. Adding foamy algaecides will just use up lots more chlorine. Polyquat could help, but it will be expensive, and you'd need to limit chlorine levels to something below 10ppm. And, it really works better if you've got a working circulation system, which you don't have at present.

If worst comes to worse, there are other ways. But they have complications and side effects. So, try chlorine first.

Ben

PS: Remember to add chems all around the pool, if your circulation system's not working. Pre-dissolve any borax in hot water.

[donjoarm]

OK. It's been a week and I have put 14 gallons of bleach in my pool over that time. I have the filter on recirculate since it continues to block every 20 minutes or so. The water is stilll green but the chlorine level remains high. Do I stay this course? I am brushing regularly as well. Thanks for the input.

[duraleigh]

Don,

You will have little success unless you get a drops based test kit and can test your water several times during the day. With that very high CYA level of 100, you need to put enough Cl in there to bring it to 25ppm and KEEP IT THERE until your water clears. As long as your water is green, you're not keeping your CL high enough.

Dave S.

[donjoarm]

I am beginning to get confused. One person is telling me to boost chlorine to 15 and add more when I get to 3 ppm and now I am being told to raise it to 25 and keep it there. Which is correct? How high can I raise my chlorine in a vinyl pool?

I do have a drop test kit but the highest it reads is 3 ppm. Where can I get one which will read 25?

Thanks.
Don

[duraleigh]

Don,

with a CYA level of 100, you will need to be around 25ppm to get to shock level for your pool. It then starts down immediately. Keeping it way at 25ppm as often as you can will accelerate the time frame it takes to clean your pool. I think the 15ppm level was recommended without noticing your CYA level.

If your test only goes to 3ppm it doesn't sound like a drops-based test. Go to Walmart, Lowe's etc. Better yet, spend the bucks and get Ben's kit...it's all you'll ever need.

Dave S.

[donjoarm]

Don,

with a CYA level of 100, you will need to be around 25ppm to get to shock level for your pool. It then starts down immediately. Keeping it way at 25ppm as often as you can will accelerate the time frame it takes to clean your pool. I think the 15ppm level was recommended without noticing your CYA level.

If your test only goes to 3ppm it doesn't sound like a drops-based test. Go to Walmart, Lowe's etc. Better yet, spend the bucks and get Ben's kit...it's all you'll ever need.

Dave S.

Dave-

If by drops based kit you mean the kind in which you add drops of OTO solution and compare the color with the samples, that is what I am using. Lowe's carries these kits which max out at 3 ppm and the Walmart kits max out at 5 ppm.

Is there another type of drops based kit? How high will Ben's kit read?

I have owned a pool for 13 years and have never had this type of problem so it is really driving me crazy.

Don

[waterbear]

Dave-

If by drops based kit you mean the kind in which you add drops of OTO solution and compare the color with the samples, that is what I am using. Lowe's carries these kits which max out at 3 ppm and the Walmart kits max out at 5 ppm.

Is there another type of drops based kit? How high will Ben's kit read?

I have owned a pool for 13 years and have never had this type of problem so it is really driving me crazy.

Don First (I appologize if you already know this but sometimes it's good to start with the basics, I also appoligize for this being somewhat lengthy:rolleyes:) there are 3 types of chlorine that needs to be measured:
Free Chlorine (chlorine that is available to act as a sanitizer)
Combine chloine (chorine that has combined with organics in the water and is usually not an effecient sanitizer)
Total chlorine (the total of both FC and CC)

Both FC and TC can be directly measured with the proper tests. CC is found by subtracting the FC from the TC. Ideally your FC and TC measurements should be the same. If they are not it is time to shock.

There are acutally different drop based reagents to test for chlorine

OTO (turns yellow) only measures Total Chlorine. Some people say that if you read it in the first 15 seconds it will give you a free chlorine reading and then let it sit for 2 minutes you can get a total chlorine reading but, IMHO, the results just aren't accurate (Walmart test kit has this in their instructions). It is good for a quick check on your chlorine levels when you know there are no problems or in some situations like yours as PoolDoc indicated.

DPD (turns pink) can measure both Free chlorine and Total Chlorine. It is a much better test but it has drawbacks. the differences in color are sometimes difficult to detect (especially for men) and it can 'bleach out" (turn clear) at chlorine levels above about 10 ppm leading you to believe that you have NO chlorine in the pool when you really have a lot! This can be overcome to an extent by diluting the sample with distilled water and multipling the reading by the dilution factor but this reduces the accuracy and can be time consuming. (dilution can also be used with OTO in the same way andhas the same problems)

FAS-DPD (also pink) is a titration test (pink color will turn clear to give you the reading...endpoint is DISTINCT) that can accurately measure very high chlorine levels (both FC and TC) (up to 50 ppm I believe) with an accuracy up to .2 ppm Combined Chlorine. It takes a bit longer than the other 2 but the results are easier to determine and much more accurate at high clorine levels, which is important when you are dealing with the type of problem you are having.

The general consenus that I have seen on this board (and I agree with it) is that OTO is good for a quick check and that FAS-DPD is good for actually determining your FC and TC.

Ben's kit which is sold on the sister website www.poolsolutions.com (http://www.poolsolutions.com) has both OTO and FAS-DPD tests in it. Taylor K-2006 is an FAS-DPD test kit. Either one is good. Ben's is a 'better bang for the buck'!:D

Both Pooldoc and Duraleigh are saying the same thing and it is sound advice. With the type of chlorine demand that you have your chlorine levels will be constanly dropping. You can put the bleach in your pool and then test it later and the level will be down! Algae creates a huge chlorine demand! You need to keep the level up and keep getting it back up.

Pooldoc's post is certainly is worth following since he is our forum moderator and has the experience to back up what he is saying. Dump in at least the amount of bleach he says and keep testing the water with OTO (since you will certainly have combined chlorine and you are really only interested in the total chlorine at this point) and EVERY TIME it drops below 3 ppm add more bleach. This could be several times a day. His note on pH and whether the pool opened with no CYA or high CYA is important. You never stated if the CYA levels are because you just added stabilizer or if they are from before. (the reasons are VERY technical but if you do what he suggests it will certainly be helpful!)

Once the pool clears and your filter is working might then be the time to start testing for CC and to keep the bleach levels up until it is 0 ppm.
As Dave (duraleigh) stated in his post, with a current CYA of 100 ppm you might need to go up to about 25 ppm FC to achive this. This is based on Ben's (PoolDoc) Best guess CYA chart. Here is that thread:
http://www.poolforum.com/pf2/showthread.php?t=365

[mwsmith2]

EVERY TIME it drops below 3 ppm add more bleach.

The water should be kept at 25 PPM until the algae is killed off. If you've let it drop to 3 ppm, you're going to be playing with this for a LONG time. Get it to 25 PPM. Keep it there until the pool clears. Once everything dies off and drops out, then you can slack off a bit, down to maybe 15 ppm until the water is clear.

Michael

[waterbear]

Michael, I was quoting from Ben's previous post on the subject and I defer to his knowledge and experience.

[donjoarm]

Thanks for all of your replies. I still have all of the same problems mentioned above (filter short cycles, water is still green). However, I ordered Ben's kit and can now actually test my water. Here is where I am now (after adding 3 gallons of bleach due to original TC reading of 13). Today is the first I have added bleach in over a week while I awaited the arrival of the test kit.

FC = 35
CC = 1
TC = 36
pH = 7.2
Alk =80
Cya = 60

How long should I continue to maintain these cl levels?

Thanks.
Don

[duraleigh]

Hi, Don,

There's a typo or calc issue. 3 gallons of bleach to your pool with a Cl of 13 should've brought you up around 22ppm....you show 35. Review your post....we need to find that error.

Secondly with a CYA level of 60 (not 100 that was originally posted), your Cl level only needs to be brought up to around 18.

Lastly, the CC of 1.0 indicates you still have "bugs" that your Cl is working on. When that CC goes to 0, your water should be pretty clear.

The only thing I can help with the DE filter is you're still filtering out dead algae......I simply have no DE experience.

Get us that corrected Cl number posted back.....don't put in any more Cl 'til we find that error. :)

[donjoarm]

You are correct Dave. I thought my second reading was rather high. I tested again this morning and the results are:

FL = 17
CC = 1
TC = 18
CYA = 60

The original CYA reading was from the pool store. I have read it twice now and it has been 60 both times.

Don

[donjoarm]

Thanks for all of your replies. My water is clear and the filter is running fine. I will continue to rely on my local pool store, but I will do my own water testing from here on out.

[edarling]

I am having a similar problem - I have a DE filter that is getting clogged constantly - even after bumping, draining, and adding new DE there is no circulation. I need to take it apart and clean the fingers at some point. That is a pain with the Hayward DE filters with the 15 bolts, but I'll do it every few days if my pool cleans up!

My question for you is - did you add all the bleach without running the filter? I can't seem to see that answer in your posts. Ben's response seems to say it is OK to add the bleach until you can see clear, then vacuum to waste the stuff that falls out to the bottom. How did you run your filter if it had no pressure. I really need to know, since I am encouraged that you finally got your pool cleaned up. My situation is very similar and that is my main question.

[donjoarm]

I have a Hayward multiport valve which allows me to bypass the filter by placing it in the recirculate position. I continued to circulate the water without filtering. I believe the post by PoolDoc indicates that you should still add the bleach until the algae is dead if you are unable to recirculate.

The most important thing I did was obtain a test kit which allowed me to know exactly what my CYA and chlorine levels are. This was the only way to determine what the necessary "shock value" is for my CYA level. Once you hit that Free Chlorine number and keep it there for a couple of days the algae will die.

Good Luck.

[edarling]

thanks for the reply. I don't have a multiport valve that allows recirculating, so that is not an option. I am adding lots of bleach and testing everything. I am seeing progress, but not as fast as if I was using my filter. I am using my Aquabot to clean the stuff out from the bottom, and it does circulate that water somewhat.

All the rain in my area (14 inches in some areas in MA) over the past weeks has really been a problem with pH and Alk, but it is good to allow vacuuming to waste and refill without using my well pump. WHen it stops raining, I will clean the filter and start circulating (I hope) with it. I'm hoping it will only take a few attempts at taking the thing apart and cleaning it.

- betty

[brent.roberts]

Edarling

It is not an extravagent expense to change the valve to the multiport that will allow you to recirculate. I think maybe $ 100. Check it out.

Secondly, some well written authors and myself, think that the Hayward DE filters with their bumping are a bad joke. The prinicpal is that you start with a clean filter, add DE and then run the system until the pressure builds up, then bump it. The pressure went up because the filter got coated with debris. When you bump it, you knock all the DE and debris off the membrane into a sloppy slurring the bottom of the tank. Then you re-start the system and the whole mess re-coats the membrane. All the debris, organic and otherwise is still in there !! The organic stuff is still going to consume your chlorine, inside the filter.

If you're having problems, forget the bumping. Backwash it and get rid of the contaminants. You'll clean the pool up much faster.

But, to really kill of algae you need lots of chlorine, in other posts above, but you really need to keep the water circulating to keep the algae exposed to the chlorine. Brushing helps too. So the valve with the bypass/recirulate setting will really help till the problem is cleaned up.

[expose]

You'll probably get better results with low pH (~7.2) than with high pH (> 7.6) . . . UNLESS you had high CYA when you closed the pool, and now have low CYA. (Test to find out!). In that case, you'll need to RAISE the pH to around 8.0 with borax before you began dosing with chlorine. You'll get very fast algae kill, in that case, but you'll have to continue adding chlorine long after the water is clear, to get rid of all the chemical residue from bio-degraded CYA.
1)What do you do if you don't know what the CYA levels were when the pool was closed?
2}What would be the effects of having "all the chemical residue from bio-degraded CYA?"
3)How much chlorine would you add, and for how long after the water is clear?

[waterbear]

1)What do you do if you don't know what the CYA levels were when the pool was closed?
Don't worry about it and get your CYA level correct. (See second answer for what will happen if your CYA was biodegaded.)
2}What would be the effects of having "all the chemical residue from bio-degraded CYA?"
You would have a lot of ammonia compounds and urea in the water and your chlorine levels won't hold. You will also have a lot of combined chlorine.
3)How much chlorine would you add, and for how long after the water is clear?
You would add enough chlorine to bring it to shock level for the amount of CYA CURRENTLY in your pool (see this thread http://www.poolforum.com/pf2/showthread.php?t=365 )
and KEEP IT THERE until the Combine Chlorine is 0 ppm and your FC is holding. This might take a while and a LOT of chlorine!

Hope this helps.

[edarling]

Back to my original problem of clogged DE filter. I finally went out to undo the 15 bolts in my DE filter, and hose down the fingers. The DE was sooooo gummed up - it was like putty. I don't know what got into the filter to make it that clogged up, but it took a hose spayer on full force to get it out. I only added shock (for conveinience factor), bleach, and ph+. The algae was still active when I started the filter, so maybe I should have really shocked before using the filter to filter out the dead stuff.

Now I can re-add DE the normal way by draining to waste periodically, and the pressure is back to my pool's normal. I can do the normal to clear up the pool - add bleach to shock levels, vacuum, retest, repeat. WHen the pool is clear, I'll open the filter up again and clean it again for the season.

It does filter much faster with the filter than with my Aquabot :) I can almost see the bottom of the deep end. We've gotten so much rain this week (about 7 inches here, but lots more in other parts of NE) it has been hard to get the pool work in.

-betty