New pool owner with green pool.

[herysoe]

hi all, i am new in maintaining a swimming pool. the pool is kidney shape with 30000lt, using salt chlorinator and sand filter. after coming back from overseas, my pool welcomed me with green pool. So I went to local pool shop and here are the result:

0 chlorine
7.7 ph
160ppm hardness
0 alkalinity
10ppm CYA

so they gave me list to add and I did them. add chemicals here and there..3 days later my pool is better, very light green. close but no cigars yet....so i went back to pool shop and here are the new result:

0.1ppm free chlorine
0.4ppm comb chlorine
7.1 ph
250ppm hardness
130ppm alkalinity
15ppm cya
300ppb phosphate
5000ppm salt

so far, looks like i haven't add enough chlorine to the pool. So the pool shop gave the list todo again. I am currently adding hcl to lower the alkalinity so that the ph will increase. next step then to add more chlorine..
my questions:
1. is there any difference adding granular chlorine or liquid chlorine? as I may be able to buy cheaper liquid chlorine in gallons as to granular chlorine.
2. during this process, should I run the filter for 24hours or 12 hours..the steps from pool shop doesn't really say..
3. is my assumption correct, the pool still showing very light green because the free chlorine still not high enough? once they are high enough, then the pool should looks better..
4. one of the suggestion from the pool shop was to add filtrite salt water boost which is sodium dichoroisocyanurate..to superchlorinate the pool. it isn't adding granular chlorine will do the same job as well?

Please help..thank you

[coolclearwater]

Remember, the pool supply store has only one goal in mind.... to sell you lots of stuff! All you need to turn a green pool clean in shock and liquid chlorine. About 4 lbs of calhypo or dichlor and about 8 gallons of liquid chlorine... plus about three filter cleans. Clean your filter at the beginning of the process, during the middle and once again when everything has cleared up.

It is also important to brush the pool often during the clean up process. Yes, run the filter 24/7 until all is clear.

Most importantly, keep chlorine residule at 5 during the process.

To raise Ph, use eith soda ash or sodium bicarb.
As to your questions....
1. Chlorine is chlorine.... some is stronger than most. Liquid, if it is fresh is 12%, calhypo is 65% ! Which is why it is such a good shock.
2. run filter 24/7... again, make sure it is clean.
3. Yes, the chlorine is what is killing the green algae.
4. Remember.... all they want to do is sell you stuff, lots of stuff and then more stuff.
5. For best results, hire a pool service professional.

[chem geek]

Chlorinating liquid or bleach is good to use, but be careful if you use other chlorine products. If your CH is already high, you don't want to add Cal-Hypo. Unless your CYA is too low, you don't want to add Trichlor or Dichlor. In your case, your CH is not too high and your CYA is on the low side so you could use either product (within reason). The following are chemical facts that are independent of concentration of product or of pool size:

For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by at least 7 ppm.

So with Dichlor, in particular, don't add too much. If you use it for continued shocking, you could end up getting your CYA too high, but right now your number is low so it's OK to use.