Pool Owner Woes – FNSP60 Pressure & Algae

Problem: Recurring algae – Pressure in filter jumping from 17 PSI to 35 in 1-2 hours

Background:
I purchased a home with a pool about a year ago and have been battling black algae since day 1. This has been managed for the past year effectively enough through blood, sweat and tears. It is a 60x10 lap pool using an FNSP60 DE filter. I have a number of mesquite trees nearby and have quite a bit of organic matter to deal with on a daily basis. I normally had to backwash about every 2 months (last year swim season).

Last month I got back from a business trip (5 days) and the pool had turned green. We have not been able to get it stable since that time. I am consistently dealing with high pressure in the filter with little to no water movement and new green algae growth. I have a company managing the chemicals on a weekly basis (which turned into twice weekly the last 2 weeks). They are putting 4 times the normally required chlorine for a pool of that size including conditioner and it is not “taking”. Zero FC after 2-3 days. I have a side suction pool Shark and brush daily for the black algae. I have taken the filter apart and cleaned thoroughly after backwashing. I have also spot cleaned the grids with the lid off twice during the last month after backwashing. Still no positive results.

I introduced Algaecide for the first time 2 days ago (against the recommendations of the pool chemical company) with initial positive results. I can now see the bottom of the pool and most of the top layer algae has either gone into the filter or dropped to the bottom of the pool. I backwashed again (adding more DE) only to have the pressure spike to 35 PSI after 2 hours. I am going through D.E. like crazy due to how often I am backwashing and cleaning the grids while making very little progress. I’m hoping to find a better management strategy to get this under control. Is there anything I am missing that could be causing the pressure to sky rocket so shortly after a backwash with fresh DE? I normally add 7 lbs.

Possible issues and next steps I am thinking about:
- Replace D.E. filter grids
o I am NOT seeing DE in the pool and do not believe I have a hole in the grids but the plastic “skeleton” on many of the grids are damaged and broken in part.
- Filter Grids placement in filter
o The grids are sandwiched very closely together against the vertical pipe. I am concerned there should be more room and this has contributed to the damaged “skeleton” of the grid as described above.

I’m hoping someone who has gone through similar issues will have some insights on a better/different strategy I could be using on the pool maintenance.

A major problem I am thinking that you may have is the fact that live algae clogs DE filters up almost immediately. You are best to shock the pool and then put your filter on recirculate until the algae is dead. I don't know about "damaged skeletons" but maybe someone else will chime in here who does.

A couple of other things that I am noticing as maybe contributing to your problem:
-- pool is receiving maintenance only 1 or 2 times per week. (When you are fighting algae, it is everyday battle or else the algae wins.)
-- adding algaecides can cause issues. The only algaecide we recommend is 60% Polyquat.

We will need some good numbers taken with a drops-based kit. If you don't have a good drops-based test kit, you need to get one.
The test kit that we think is by far the best is the Taylor K2006 or 2006C (better buy). Not available locally but you can get it through this link that takes you to Amazon: http://pool9.net/tk/

But, in the meantime, go to Walmart and see if they have the HTH 6-Way drops-based kit (no test strips!) and get that. If they don't, get an OTO/Phenol Red kit (yellow and red drops) instead. Use it to test and then post your numbers. Also while you are at WallyWorld, get several jugs of their generic 8.25% bleach and a couple of boxes of 20 Mule Team Borax (laundry aisle).

We also need to know exactly what all has been added to the pool meaning ingredients and not just product names like 'shock' or 'algaecide.'

(One other thing that is likely to be problematic for us in helping with your pool is that it is difficult for us to offer advice to a homeowner when there is a pool company also involved. Mixing and matching our advice along with what they may or may not be doing usually doesn't work.)

Welcome to the Pool Forum!

Just to extend what WaterMom said, until you kill the algae, you can't really tell if something's wrong with your DE filter. The problems of dealing with live algae using a DE filter are going to overshadow everything else.

If you had not used an algaecide, we'd just recommend that you add sufficient chlorine to kill the algae -- given that you may have mustard algae, that might be a LOT of chlorine. But you said the algaecide was "effective" which means there's a good chance it was copper based. That, in it's turn, means that adding sufficient chlorine to 'do the job' is likely cause the copper to stain your pool..

Anyhow . . . membership updated.

Thank you both for the information. I purchased a drops based kit from Ace Hardware over the weekend. I was planning on using it after getting the algae under control. After treating with the KemTek Algaecide (http://www.kem-tek.com/kemtek_produc...een-algaecide/) with positive results I added 5 gallons of generic standard bleach. The next day I treated with HTH Algae Guard Concentrate (http://www.amazon.com/Arch-Chemical-...rd+concentrate ). A day later it looks like the Algae is making a come back. It was treated yesterday by the chemical company for it's weekly shock. I am canceling the pool service.

I ordered new grids for the filter today. I would like to get the algae under control before using them but that may not be possible. I purchased HTH Super Select Shock treatment and was planning to introduce that tomorrow. I also ordered Algaecide Prevent Polyquat 60 (on your recommendation) along with a supply of Pool Shock Power Blast (68% Cal Hypo)

I am concerned that I will continue to clog the DE filter while fighting this battle (it clogs in hours and I cannot babysit it all day). I don't believe I have an option for recirculate on my filter. Is this only available with multiport valves? It looks like I also have some reading to do on use Borax on the pool which I have not been aware of until now.

Quote:

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I was planning on using it after getting the algae under control.

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How does THAT work? You're going to find out what you're working on . . . after you finish working on it??

Get a kit, now! Test the water, now! Tell us what's there, now! (Right now, you are flying blind, at low altitude, around mountains!)

The good news is, none of the algaecides you've used are a problem. In fact, they are all the SAME thing. The Kem-Tek Polyquat (60%) is just the concentrated version of the other two products which are both a 50% dilution (30%). The bad news is, they aren't really going to help you in your current situation. So save what you have to use AFTER your pool is cleaned up, when you go on vacation.

Using the 68% cal hypo CAN help, if you used it correctly. But you need to know more, and I need to see test results, before you try to use that. Depending on your current pool water conditions, it could make things worse.

Since I really don't know what your current water chemistry is, the only SAFE form of chlorine to use is bleach. Assuming your water depth averages 4 feet, you have about 18k gallons, and a PF of about 7. So . . . each gallon of plain 8% household bleach will add a little more than 4 ppm of chlorine.

1. Buy a cheap OTO / phenol red drops kit (unless that's what you have.)
2. Buy (24) gallons of PLAIN store brand 8% bleach.
3. Add (6) gallons tonight. Test the chlorine in the AM -- if the chlorine level is not ORANGE or orange-tinted yellow, add a gallon of bleach VIA THE SKIMMER after making sure there are NO other chemicals present in the skimmer.
4. Complete the info forms:

http://pool9.net/pf-pool-form/
http://pool9.net/pf-hist-form/

5. If you haven't already, order a K2006: http://pool9.net/tk/
6. If you expect to take more multi-day vacations or business trips this swim season, order the Taylor phosphate testkit, too. (same link)
7. Test your pH the evening AFTER the first (6) gallon dose, then test chlorine. Report results. If the algae has not died OR if the chlorine level is not DARK yellow to ORANGE, add (6) more gallons VIA THE SKIMMER.
8. Post results.