quantumchromodynamics

Another alternative to bleach is lithium hypochlorite. It's a bit expensive, but at the amounts used for a hot tub, it shouldn't be too bad. Can you post a full set of chemical readings, including cyanuric acid? Free Chlorine Combined Chlorine pH Total Alkalinity Calcium Cyanuric Temperature Are you using MPS or dry acid (Sodium bisulfate)?

I recommend that you get one each of the following extra reagents: R-0870-I DPD Powder, 10 grams R-0871-C FAS-DPD Titrating reagent, 2 ounce bottle. R-0013-C Cyanuric acid reagent, 2 ounce bottle. R-0004-A PH indicator solution 0.75 ounce bottle

I found this Owner's Manual. If it is not the right one, you could contact them and order the correct one. http://www.myroyalspa.com/supports/contact_us.asp http://www.royalspa.com/contact.html http://www.royalspa.com/spas/knight.html

It's important to maintain a positive CSI to prevent the plaster from dissolving. Although, it is also important not to allow the CSI to go too high. I recommend that you maintain a CSI of between 0.0 and 0.4. You can use the Pool Calculator to calculate your CSI. I prefer to keep the pH between 7.6 and 7.9.

I really don't see any reason that plaster would need to be acid washed, ever. Proper maintenance should keep the plaster in good shape. I think that acid washing should be avoided, if at all possible. Proper maintenance will prevent scale. Metals should be removed before the water is introduced to the pool. Many metal stains can be prevented with sequestrant. An ascorbic acid treatment will remove most metal stains. Of course, it requires very good maintenance of the pool and chemistry, but I don't think that it should be considered beyond what a homeowner should be able to do.

I wouldn't consider SWG to be less expensive than a manually dosed pool. By the time you buy the system, the salt, and replacement parts, the cost is usually more. The biggest benefit is convenience.

Two colored wires should be 240 volts. 120 volts would have a white neutral. Double check with a meter. Yes, they do come wired for 240v. It is easy to change to 120v. For some motors, you have to change two wires. The diagram is on the motor label. For other motors, you just turn a switch in the back. Use Photobucket and post the link.

Here is a good resource for information about plaster. It is the National Plasterer's Council.

I suspect test error. I recommend that you redo the test according to the instructions posted here. The test can be somewhat confusing. Either way, the 10X breakpoint formula is wrong and should not be used. You should not be using dichlor once your cyanuric acid reaches 20 to 30 ppm. What is your cyanuric acid level? Right now, add enough regular, unscented 6 % bleach or liquid chlorine to reach 20 ppm. You can use the Pool Calculator to calculate the correct amount of bleach or liquid chlorine to add. I recommend that you read the following posts: Nitro's Approach to Water Maintenance Dichlor/bleach Method In A Nutshell Here is the rule of thumb for adding oxidizer based on tub usage.

I would eliminate the main drain and get an automatic pool cleaner.

My opinion is that you should almost never have to acid wash. As long as you maintain good chemistry and keep metals out of the water, I don't see any reason to ever have to acid wash. I don't think that acid washing should be considered something that needs to be done periodically. With the proper chemistry, you should be able to get up to 20 years on your plaster.

I would recommend starting with a 20:1 acid mix and only increasing the concentration if necessary. Acid will reduce the life of filter grid fabric so you want to minimize the exposure as much as possible. After using acid, you should neutralize it with either sodium carbonate or baking soda before discarding it. 4.57 pounds of sodium carbonate (aka "Washing soda") will neutralize 1 gallon of 31.45 % muriatic acid. Na2CO3 + 2HCl --> 2NaCl + H2O + CO2 7.33 pounds of baking soda will neutralize 1 gallon of 31.45 % hydrochloric acid. NaHCO3 + HCl --> NaCl + H2O + CO2 Be careful when neutralizing. The carbon dioxide bubbling will tend to cause the mixture to foam. Add the baking soda or sodium carbonate slowly while stirring. If you add too much too fast, the mix could create enough foam to overflow the bucket and cause a big mess.

You really don't want to try to do anything like this. It would not work. What is it about your plaster that you are not happy about? Is it already blue? Are you getting any scale?

There are many types of sand. You say that your property was formerly a sand mine. That adds another level of complexity. Without an expert opinion, you are taking a big risk. You might get lucky and everything will go well with no problems, or it could be a complete disaster. An engineer can evaluate the situation and do any necessary tests, such as a core samples and compaction tests. As I referenced in my previous post, the example of the person with sinkholes is very informative. The builder is trying to tell them that it's normal for the pool to develop sinkholes, and the person is now in a bad situation. If they had gotten an expert opinion, then it is much less likely that they would be in this situation. Now, most pools do not require an engineering survey. However, your concern about the stability of the soil is a good indicator that it is probably going to be a problem. I doubt that you would have posted your question unless you felt that there was a good reason to be concerned.

You need to disassemble the filter and clean it carefully. Check for any damage, such as tears or rips in the fabric. Your reference to backwashing everyday suggests that you are not operating the filter correctly.

It's quite common for water to be clear while there is mustard algae. Mustard algae is powdery and tends to not stay in suspension. It is not extremely rare to have mustard algae in a vinyl pool. What is there about the composition of the vinyl that makes you think that mustard algae would be inhibited? What reference can you provide to support your hypothesis that the composition of the vinyl would inhibit algae? What scientific explanation can you provide to support your hypothesis that the composition of the vinyl would inhibit algae? Ask your pool guy what he thinks it is. What is your explanation for what this is? It's mustard algae.

I see neon green in the pictures. Here is another picture of mustard algae. In this case, the mustard has been vacuumed and brushed from its normal locations. Mustard algae is like a dust. The pattern you see is from loose algae falling out of suspension and settling back down Any pool type can get mustard algae.

Yes, I can. Mustard algae has a very distinctive color. I am 99.9 % sure that that's what it is.

I have been doing this a long time. It's not something that can be explained other than experience.

It looks like mustard algae. Can you post a full set of chemical readings and a list of all chemicals that you use? You should run your filter 24/7 and maintain shock level until the algae is completely gone. You should not need to backwash every day (sand or DE).

Good job on fixing this.

I recommend that you consult with a geotechnical engineering firm to help you determine the best way to build this pool without having problems. You should also be careful to negotiate a contract that specifies exactly what the pool company is responsible for as far as design, engineering and construction. The contract should also specify what the warranty will be. Your "Request for Proposal" should be as complete and detailed as possible. This will help you avoid situations such as this post "Crack In New In Ground Vinyl Liner Pool...normal?".

Have you verified that the unit is receiving power?

Here is the manual. If this doesn't answer your questions, please post back for further help.