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Have you considered polyaluminum chloride? If you can provide more details, it would be easier to help.

I like the idea, but I agree that the diffusion rate may be very rapid. I can offer a suggestion, which I have not tried and do not really know its chances of success. You can add a membrane of sorts to slow down the permeation rate. If you can get a piece of silicone rubber sheeting, or even...

What was the cost of RO vs drain and refill?

Just to add a bit more insight, I wanted to comment on what OnBalance commented on with respect to sodium hydroxide. Sodium hydroxide only forms calcium carbonate from carbonate ions. It does a really good job of doing so, as long as there are available carbonate ions in the water. If the pH...

I would suggest that you do a bit of "kitchen chemistry" before you try this for real. Just take a liter or so of pool water and do a scaled down version on the one liter. You will need to use a small scale to weigh out the sodium carbonate and you need to do a bit of math. I think you will...

I am probably splitting hairs at this point, but here is a bit more. Yes, sodium hydroxide can precipitate out magnesium hardness as well as carbonate hardness. Magnesium ions are not generally a problem to just keep in solution as they will not really contribute to any real world pool scaling...

I would like to add a word of caution about this method of removing calcium. In chemical engineering terms, this is referred to as "lime softening" or in some cases "pellet softening". Yes, it chemically works as stated. Sodium Carbonate is a good chemical for this. Sodium hydroxide is very...

Matt, Thanks so much for this advice. I reviewed my old pool construcion receipts and there is reference to Gemstone as the pool finish. I am not certain that it was, in fact used, but it looks a whole lot like what is shown on the internet as the Caymen Bay w/abalone finish. Of course, I...

I added two bottles of sequestrant when I was refilling to prevent metal staining. I had/have what I believed to be copper and iron issues which is why I drained and refilled. I would like to monitor the dehp to make sure that I maintain some minimum level of it without over doing it..

Thanks again. Yes, I am familiar with these methods. My salt test looks identical to the K-1766 shown in the link. I will purchase the chlorine test that you suggest. I hope my free chlorine goes up soon. Do ypu know of a good hedp test kit?

AJW, Thanks for the offer to advise. I updated my signature to show that I have a Goldline/Hayward SWG with a T15 type cell (generic replacement). I just finished filling the pool this morning, so the chemistry may be in a state of flux. Here are the results I just took to answer your...

Matt, Thanks for the input. I don't like to name names, but one person was from the industry with lots of experience. This person said that flagstone contained metals. My Google Home assistent said that it was, in part, held together by iron oxide. The flagstone and other stones are built...

I just drained and refilled my pool after doing an ascoric (and citric) acid treatment to help remove some metal stains. Some stains remain, but things are much better, and today, the water itself appears to be very clear. I added a sequestrant at the start of refilling and then kept adding a...

Matt, Thanks. I did not know about the degredation of peroxide at the high pH. Now I know. I concur with your assessment.

A recent San Diego water quality report shows essentially no copper in the water, and I believe them. My kitchen RO water shows zero copper, which is to be expected. My kitchen taps shows copper using the LaMotte test. Yes, I have copper piping in the house and it may be a source of copper...

I can add a comment that may or may not be helpful. I use sodium percarbonate to kill algae in my Koi pond. It almost always leaves behind a lot of calcium carbonate precipitate at the bottom of the pond, which is sort of a problem, but managable. It does, of course, produce a lot of hydrogen...

I have been experimenting with my pool, probably more than I should. Recently, I let the PH go below 7, which was a big mistake. I mobilized a lot of previously plated copper on my pebbletec. Bringing the pH above 87 caused much of the copper to replate on the pebbletec. I am not using a...

Can you try to remove one to see if it will dissolve with fizzing in some vinegar? It it dissolved and fizzes it is likely calcium carbonate and can be removed chemically. If not, it is probably something else.

Yes, it is a limited market. Look up the rates in San Diego. You will be shocked. I think it would be over $150 for that same pool. There is the convenience factor also. It is not always so easy to simply dispose of 15,000 gallons of water and then to refill. Convenience is worth something.

It should cost much less than RO except in the case of really high CYA levels. Of course the RO process takes out a lot more. Based on what your comments it might be interesting to try to get some actual pool water samples to test myself. I am not in the pool business so it may be hard to get...

Re: Typical measured "high" CYA levels? Hi Donldson, Thanks for your thoughts. I am sorry that I never really updated the group on my further efforts on activated carbon. It did work, but even with the high prices of water in San Diego it would not be less expensive than draining...

Hi, I am tinkering with a method of removing CYA without draining. It is different than the current methods, such as RO and microbes. I am not in the pool business, but I do own a pool and have a good background in the appropriate water chemistry. I was wondering if anyone had any data...

I have a very large spa that takes a very long time to heat up. The deep end is six feet deep and the shallow end perhaps just about three feet or less. Cold water from the bottom of the deep end travels via the bottom drain to the pump/filter/heater. The heated water is returned to the...

I am trying to figure out if about 900 to 1000 RPM is really the best RPM range for maximum efficiency in terms of gallons pumped per kwh of electricity for an Intelliflo pump. I tried to gather some data from my system and got about 35 GPM (calculated from XLS spreadsheet) for 800 RPM and 116...

Thanks for your observations. I will try to somehow circulate spa water next time, but I do not have a skimmer there. I do have a spillway, so I may still be able to use the skimmer.

This question has no real practical use, but I will ask it anyway. I have used small DE filters for fish tanks, and it is necessary to recirculate the water in the filter a few times to build up the "filter cake" before the water becomes clear. This seems reasonable to me, as the filter mesh...

I have more homework to do. The outlet would probably be 4 inch pipe, 100 feet of length with either no elevation difference, or perhaps up to negative 5 feet of elevation. Thanks for much, mas 985.

For example, lets assume that I want to pump 666 gallons per minute. Let's further assume that I use a gasoline powered pump that can pump this much, as I do not have anything specific in mind yet. Let's also assume that it will need to be pumped up a 5 foot elevation and the length of the...