Nitrates are algae food and the only way to get rid of them is by replacing water. Your test readings are suspect, btw. There is NO pool water testing that has a precision of 2 decimal places and I suspect that yours was done with test strips in a reader, correct?
Assuming that your CYA IS above 100 ppm (which is probably is if you have been using dichlor and trichlor exclusively) yo need to use bleach or liquid chlorine to get your FC above 25 ppm (and it probably needs to be closer to 100 ppm). In a 36000 gallon pool this would be about 15 gallons (or 19 96 oz jugs) of 6% laundry bleach so if 12.5% pool chlorine in refillable carboys is sold in your area it will probably be a more economical solution. The carboys are normally either 2.5 or 5 gallons and I would suggest 3 of the 2.5 gal size ( or 1 and a half of the fivers).
It's much easier to answer your questions, when we know something about your pool. We often 'waste' the first few posts back and forth collecting information. So, please complete our new Pool Chart form -- it takes about 30 seconds, but will save much more than that.Pool Chart Entry FormA few more things:
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+ Get a cheap OTO (yellow drops) / phenol test kit, or if available at YOUR Walmart (check availability), get the HTH 6-way DROPS test kit, which is compatible with the Taylor K2006. Test the pool as soon and you can, and post the results. If you get the 6-way kit, ALSO test the water you FILL the pool with, especially if it's a well, and post THOSE results as well. (The HTH is the best available kit you're likely to find locally, but it's not the K-2006. It can only provide rough measurements chlorine levels above 5 ppm, and it measures "TOTAL" hardness, rather than "CALCIUM" hardness, which is not ideal.)
+ Having a good test kit makes pool care easier for EVERYONE. A good test kit means a kit that can test chlorine from 0 - 25 ppm, pH, alkalinity, calcium hardness, and stabilizer with reasonable accuracy. Test strips (AKA 'guess-strips' ) do NOT meet this standard. Some pool store testing is accurate; most is not. The ONLY way you'll know whether your pool store is accurate or bogus, is by testing accurately your own self. On the other hand, pool store 'computer' dosing recommendations are NEVER trustworthy -- ignore them. They are designed to sell more chemicals than you need, and WILL cause many pool problems.
+ We recommend the Taylor K-2006 test kit, which meets the requirements above, for many reasons. The HTH 6-way drops kit is a great starter kit, and is compatible with the K2006 (it's made by Taylor). There are a few alternatives; for example Lamotte makes an FAS-DPD kit that's OK -- but it costs 3x as much. But, we're not aware of any test that is better, and since we are all familiar with the K-2006 (and can help you with it) we recommend it exclusively ( Test kit info page )
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