kincade Posted March 15, 2010 Report Share Posted March 15, 2010 Some of you have been very helpful in answering some of my questions about getting my water balanced and I thank you for the assistance! I have a few dumb questions that don't fit into the other 2 threads I've started, and I'm hoping someone can kick me a few answers to them. I've searched but I can't seem to find the answers. Bear with me please, I'll get the hang of this sooner or later! Ok, here goes... I'm trying a 'modified' Nitro's approach with Nature2 for my 'out of town' periods and am going to try and supplement the chlorine with MPS. The tub is a brand new bullfrog with a CD ozonator. -When shocking weekly with chlorine or MPS, how long should I leave the cover off to avoid damaging the cover/pillows/etc from outgassing? Does an MPS shock eliminate CC like a chlorine shock? And do I need to leave the cover off for a while after adding chlorine every night like I do with shocking? -For those of you who add MPS before a big hot tub party to avoid raising the FC too high, how much do you add? I can't find any information on how much to add before soaking (and I understand that too much can cause irritation for some people). -I think I'm getting the CYA thing down... If I understand correctly, the CYA keeps most of the chlorine in 'reserve' and keeps it from working too aggressively. And that with a CYA of 30, keeping FC at 3 outgasses less and is less aggressive on the swimsuits/pillows/cover than keeping a FC of 1 with CYA of 0. Is that correct? If it's kept in reserve does that mean that if I let my FC drop to 0 that the CYA will start releasing chlorine and drop on it's own? Any other recommendations on keeping the chlorine and chemicals as low as possible would be greatly appreciated! Thanks in advance. Quote Link to comment Share on other sites More sharing options...
quantumchromodynamics Posted March 15, 2010 Report Share Posted March 15, 2010 When shocking weekly with chlorine or MPS, how long should I leave the cover off to avoid damaging the cover/pillows/etc from outgassing? I don't think that it is necessary to leave the cover open for too long after shocking, especially if you have 30 ppm cyanuric acid and don't shock super hard. 20 minutes should be fine. Do I need to leave the cover off for a while after adding chlorine every night like I do with shocking? Not really. You can give it 5 minutes if you want. For those of you who add MPS before a big hot tub party to avoid raising the FC too high, how much do you add? Add 1 tablespoon MPS per 250 gallons before use. If I understand correctly, the CYA keeps most of the chlorine in 'reserve' and keeps it from working too aggressively. And that with a CYA of 30, keeping FC at 3 outgasses less and is less aggressive on the swimsuits/pillows/cover than keeping a FC of 1 with CYA of 0. Is that correct? Yes. If it's kept in reserve does that mean that if I let my FC drop to 0 that the CYA will start releasing chlorine and drop on it's own? No, all Free Chlorine is measured in the FC test because the test releases the chlorine that is bound to the cyanuric acid. Quote Link to comment Share on other sites More sharing options...
kincade Posted March 17, 2010 Author Report Share Posted March 17, 2010 Thanks for your quick reply! So with a CYA of 30, is it safe to soak with a FC of 1? Or does it need to be bumped up to 10% of the CYA level? And what is 'shock level' with a CYA of 30? Does 10ppm FC still apply? Quote Link to comment Share on other sites More sharing options...
quantumchromodynamics Posted March 17, 2010 Report Share Posted March 17, 2010 Yes, 1 ppm FC and 30 ppm cyanuric is safe to use. As long as you maintain consistent FC readings and do not allow the FC to go to zero for any length of time, then you should not need to shock to 10 ppm very often; 5 ppm should be fine. Ideally, the amount of chlorine you add today should be enough so that the level is about 2 ppm by the next time you use the tub. Quote Link to comment Share on other sites More sharing options...
freeradical Posted May 21, 2010 Report Share Posted May 21, 2010 Given the general rule for requirment of 7 ppm FC/person/hour from Nitros approach, does this mean that 1 person could use the spa for approximately 20 minutes (2/7 person-hours = approximately 1/3 hour given 1 person using the tub) before the FC goes to zero? So you would have to exit the spa after only 20 minutes for 1 person, 10 min for 2 people, 6.67 min for 3 people, etc. and then add more chlorine? This is assuming that no MPS was added prior to entering the tub which would somewhat relieve the chlorine of any oxidation "duties" and allow it to be used for sanitation. Maybe I am confusing oxidation/sanitation requirements and this is leading to faulty logic. Can anyone help? Quote Link to comment Share on other sites More sharing options...
PaulR Posted May 22, 2010 Report Share Posted May 22, 2010 chem geek describes in terms of an absolute amount of chlorine per person-hour, which for any given tub can be converted to PPM but that depends on tub volume. My notes say 2.5oz of 12.5% liquid chlorine, or equivalently 5 oz 6% bleach, per person-hour. I'd put it in after a soak, not before... using MPS after a soak would also help but I don't have specifics for that. --paulr Quote Link to comment Share on other sites More sharing options...
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