cal hypo and ph

[john509]

I am using a Taylor kit bought at Walmart now. I am not sure the number because it was rebranded as HTH. The kit is OTO + phenol red. In with it were reagents for CH testing, Alkanity testing, and CYA testing. I ran out of CYA reagent so I bought a bigger bottle of Taylor CYA regent, don't recall refill number at the pool store. I am using 7 mil pool water and 7 mil CYA regent in a shake that and pour slowly til the black dot disappears in the small tube.

I am still using strips to check FC vs. total chlorine but I usually don't find a difference and the strips are giving something close to the OTO readings. I think the algae problem is more from not testing and not adding adding anything during a period of two pretty much back to back to rainstorms. We had a week of pretty heavy rains where I was not fully fulfilling duties. The CL had dropped to 0 and the PH was reading what I thought was 8.2 or higher after the rains. I got a little lazy. Breaking out the vac hose because the sweeper went into the shop also showed me the pump is not circulating as well it should, low suction, so that likely contributed. That part should be scheduled to be fixed today if I don't find anything blocking the impeller or fixed if I do.

The chlorine seems to be being used up instead of building up CCs. If there is CC it is not more than 1-2 PPM because that is where CL seems to be dropping to after adding enough to get to 6 PPM the previous evening. I usually test and add near sundown so the CL does not get burned up by the sun. The TC is dropping appropriately so I think the CL is getting used up even if my test strips may be off on this one. I just shocked Friday with 15 PPM added. The TC was down to what looked liked 3 to 6 today the range just below 5-10.

The PH test is phenol red. The comment about not testing when CL is higher than 6 or so applies to PH testing. I have read when the CL is 10 or more the phenol red test is inaccurate. Generally if I go over 6 it is 10 more so I don't bother with PH test until the CL comes back down. 6 really isn't my rule for not testing PH it is just if it over 6 I am probably shocking and it will be over 10.

The alkalinity test is one where you take 25 ml water and drop 5 drops of the reagent and then drop triant a drop at a time until it changes color. Again HTH but I believe that is actually Taylor chemicals which number they don't say though.

I do plan on buying a better kit particularly one that test FC as well as TC. I have not done so yet though.

I also do need an upgrade to check base and acid demand.

I really do not know how old the plaster is. I think the previous owner's son said it was redone a few years ago but I am not sure exactly when. It isn't new and has signs of patching some cracks but it does not look chipped but there are some areas that look kind of gray.

Part of the problem is I was not using the HTH kit for long before switching from bleach to Cal hypo so I have no idea if this was happening before. The strips seem similar in CL ranges and TA to OTO and the kit but the PH was completely unreadable and the ranges on he strips were too big on TA.

[john509]

Thinking about this, I remembered Leslie advertised some cal hypo "shock" as PH near neutral but not this one. If i can't find the spec sheet I suppose I could test tap water then add a little cal hypo and see how much PH rises. Any idea of how much water to how much powder to use?

[chem geek]

Any hypochlorite source of chlorine (bleach, chlorinating liquid, Cal-Hypo, lithium hypochlorite) will have the pH rise when you add it to the water. It is when the chlorine gets consumed/used that the pH drops back down since that process is acidic. The pH neutrality comes from the combination of chlorine addition AND consumption when you end up back to the FC where you started. As I noted, there is a small net pH increase from all of this, but it is usually relatively small compared to the pH rise from the outgassing of carbon dioxide caused by the TA being too high or having more aeration.

As waterbear noted, you need to deal with your algae problem first. As for test kits, get the Taylor K-2006.

[waterbear]

As for test kits, get the Taylor K-2006.

Couldn't agree more. It will pay for itself over and over again!