Filter not doing the job?

I swear I posted this a few hours ago, but its not showing up so I apologize in advance if it shows up twice.

I've been fighting an algae problem for about a week now. Here are my current measurements:

FC: 15 (this morning)
CC: 0 (this morning)
ph: ~7.7 (this morning)
CYA: ~40 (measured this past Saturday)
TA: 160 (measured late last week)
CH: 140 (measured late last week)

Initially I wasn't too diligent about my chlorine levels due to being busy with life, but I've now had my chlorine at or above shock level (15ppm) for a good 48 hours. Yesterday the water began looking more clear, but after reading the instructions on fighting algae more carefully I decided to brush my pool yesterday afternoon. This generated quite a cloud of green "dust" down in my deep end, which is where I brushed everything towards (because that is where my main drain and skimmers are). Last night I backwashed and topped off with a big bottle of walmart bleach. This morning the pool is still cloudy. I brushed and although I kicked up a little bit of debris, it wasn't nearly as bad as yesterday. I'm discouraged that my filter doesn't seem to be clearing the water because I'm pretty sure at my current chlorine levels I've got the algae killed by now. I backwashed again this morning. Oh, I've been running the filter 24/7 this entire time I've been fighting the algae problem.

One question I have is, how often should I backwash? I've seen both things recommended (not backwashing too often or backwashing daily). I should note that the pressure on my system never seems to change much. It is always around 19 or 20.

Any help is appreciated. I'm heading out to retest my chlorine levels now...

Tested my water last night and FC was 12.5, CC was zero. Added 1.42 gallons of 6% bleach, which should bring FC up to 15. This morning the water was looking clearer. I can see the drain at the bottom of the deep end (~9'). I tested the water again and FC was 13.5, CC zero. I brushed again and there is still some residue (and of course the water is all cloudy again and I can't see the drain in the deep end any more). Does this mean that the algae isn't dead or that it isn't being filtered out? This is so frustrating. I don't seem to be making any progress despite high chlorine levels and running the filter 24/7. Please help!

I'd also appreciate an answer as to how often I should backwash during this process.

Finally, I'm having trouble updating my sig. My pool size is actually more like 34000 gallons and I am using a Taylor K2006 test kit.

Forgot to mention in my last post that I added another 1.42 gal jug of chlorine. I just did another test. FC=15.5, CC=0, Ph=7.7.

Also, as my updated sig suggests, my pool volume is actually more like 27000 gallons. So 1.42 gallons actually raises my chlorine by 3.2, not 2.5, which is what I earlier thought. Assuming that is correct, my morning bleach should have brouth me up to around 16.5 and now I'm 15.5. So I lost 1ppm of Chlorine in a matter of 3 hrs. So I'm thinking the algae isn't all dead after all, which would explain why things aren't clearing up. Does that analysis sound good? (I'm assuming my CYA measurement of 40 from Saturday doesn't need to be redone yet, besides I'm running low on that reagent, but I've got a new batch on order). I'm going to start measuring chlorine every few hours now to make sure it stays above 15ppm.

i dont much about sand filters so i cant comment about backwashing, but keep it running 24/7 like you are untill the mess is cleaned up.

seems odd that you are getting a CC reading of 0 because it sounds to me like you are still fighting algae as you still found "residue" while brushing. also you lost 1PPM of chlorine in 3 hours, so something is using it. you will also need to test at night, or after the sun is off the pool, and then again in the morning within 2 hours of the sun being on the pool to see if you are losing more than 1PPM of chlorine overnight. if you are losing more than 1PPM overnight then the battle is still on!

your CYA wont change much as long as you have not added any stabilized chlorine to the pool or drained a LOT of water and refilled. if you tested 40 last week, then its probably still 40, so save you reagents for now.

this is the most important thing... test and brush often, and keep that FC above shock level AS MUCH AS POSSIBLE untill you are 100% certain all the green stuff is gone. once its all gone you will still be left with a cloudy mess. be patient and as long as your filter is working right it will get cleaned up! it took me a few days to kill off all my algae, water bugs, and tadpoles, ( actually the tadpoles were dead in minutes ) but it took a couple weeks to get clear again!

good luck!

I updated your signature, with your new data. Please note the gallons figure: it's based on a 20x40 pool with a 3.5' WATER depth and a 9' deep end (8.5' water), with a break at the midpoint, and a hopper bottom. If the break is closer to the shallow end than that, OR if the deep end is straight sided with right angle transitions from the walls to the floor, then the volume will be higher.

+ If the algae is green, you need higher levels of chlorine. If the algae is BROWN, then it's dead, and just needs to be filtered.
+ Do NOT backwash too much. Backwash when the filter pressure has increased 5 -8 psi over the clean pressure. (You do have a working pressure gauge, right?)
+ You can TEST your filter with a small amount (~1 lb) of DE powder added directly to the skimmer. If it shoots back into the pool after going through the filter . . . your filter needs work, and you may not be able to remove the algae till the filter is repaired.

I'd say the algae is green, so I guess its not dead. I'll keep going with the chlorine and try to keep it at 15 or above.

I do have a pressure guage but I kind of question if its working properly. It never seems to change. It is always around 19 or 20 psi and never seems to go up. I'm pretty sure it does go down to zero if I turn off my pump.

I'm not sure what DE powder is, but I'll look it up in the abbreviations and figure it out.

Thanks

Just tested my water again... FC=15, CC=0. Adding another big jug-o-bleach which should bring me up around 18. I'll test again b4 bed and maybe I'll add another just for good measure. Will report back in the morning.

Quote:

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Originally Posted by gogolion

I do have a pressure gauge but I kind of question if its working properly. It never seems to change. It is always around 19 or 20 psi and never seems to go up. I'm pretty sure it does go down to zero if I turn off my pump.

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Make sure it does go to zero. If it IS working, and never goes up, your filter may need more sand.

DE powder is filter powder, diatomaceous earth, used in DE filters. You may be able to get a 5 or 10# bag at a pool store.

The pressure gauge does go to zero when I turn off my pump.

I added another jug of bleach late last night without testing (I didn't see responses to this thread until this morning). I tested late this morning and FC=16 and CC=0. I'm going to add another jug soon to make sure it stays well above 15 (my shock level according to the best guess chart). I've just got to go buy some more. I brushed again this morning and the amount of residue seems a little better, but its still there. I consulted my mother-in-law and we decided the color is a brownish green, somewhere in between. Some areas seem more brown, some more green. Maybe that means its dying but not dead?

I'm also going to go by some DE powder and run the suggested test. How do I tell if my filter needs sand? Do I need to take it apart? Or is there some way to tell without that?

One other thing I may not have mentioned is that my pool leaks fairly significantly through some cracks. I normally top it off every couple of days with a couple inches of water. Today the level was close to bottom of my skimmers. I decided it may filter out more easily if there is less water so I turned off my skimmers and I'm not topping it off. Of course, my pressure dropped to 12 or 13. Is an unwise move? That is, am I better off topping off and running my skimmers or letting it be and turning off my skimmers.

I'll report back after my DE powder test. I'll also start testing late at night and in the early morning to see how much chlorine I'm losing overnight.

One more question... so far I've just been brushing, hoping the skimer and drain would pick up the debris and it would get filtered out. Would I be better off vacuuming? The problem there is that it is so time consuming. Brushing is pretty quick and easy.

Quote:

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Originally Posted by gogolion

One more question... so far I've just been brushing, hoping the skimer and drain would pick up the debris and it would get filtered out. Would I be better off vacuuming? The problem there is that it is so time consuming. Brushing is pretty quick and easy.

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I wouldn't bother with vacuuming, then, till the algae is ALL dead, AND the filter has been checked. If you vacuum with a filter that's not working well, you can end up just pumping all the algae back into the pool.