Cya(Stabilizer) Experts

[glennmacph]

Its just my 3rd fill of my new tub,arctic spa onzen(swg).Ive been baffled by chlorine production and readings with this fill,the only thing I did different was alot more super shocking with arctic spa stabilizing chlorine gradules(boost),I have a color q test kit,very accurate,but was never testing CYA

It was with these test strip that got me thinking about CYA because the color of the stabilizer section was very high 150 to 300 PPM range

The bottle of boost lists CYA in its ingredients,I think my SWG has a hard time producing Chlorine with such high CYA readings,which causes me to put more boost chlorine in it and the cycle continues.

Am I going in the right direction here,kinda new at this,the SWG is an amazing producer of chlorine when the water is new but drops off as the water gets older and I think because of this CYA thing!!!!!!!!!!!!!!!!!!!!!!

[Itchy and Scratchy]

No expert here as I use bromine, but here is what i know. You are right, it's the high level of CYA that is making it hard for your SWCG to keep up with chlorine demand. If you have not read dichlor/bleach in a nutshell at the top of the page this will bring light to the situation for you. Basicly you need to drain and refill your tub, the only way to get rid of CYA. After that go to the pool calculator plug in the gallons for your tub and a goal of 34 ppm chlorine. This will give you the amount of dichlor you need to reach 30 ppm CYA. Add this as discribed in Dichlor/Bleach. I think you will want to shock with MPS to keep CYA down.

There are other water balancing specifics as far as TA goes. I sure soon somebody else will chime in to help you out more. Hope this helps.

[chem geek]

Chlorinating granules are Dichlor and for every 10 ppm Free Chlorine (FC) that they add they also increase Cyanuric Acid (CYA) by 9 ppm. If the Boost additional lists "Cyanuric Acid" in addition to "sodium dichloroisocyanurate" or "sodium dichloro-s-triazinetrione", then the CYA would be increased even more.

As noted in the previous post, after a fresh refill you should raise the CYA level to around 30 ppm either by using Dichlor for a short time or by using pure CYA. Then do NOT add any more stabilized chlorine (Dichlor or Trichlor) nor CYA. Just use the SWG to generate chlorine and if you need additional chlorine for higher bather load then use unstabilized chlorine such as bleach. If you use the spa regularly and keep it hot, then add about 5 ppm CYA every month -- about one day's worth of Dichlor should do the trick. Forget adding anything else except acid for pH balance and baking soda if the TA gets below 50 ppm.

See Dichlor/bleach Method In A Nutshell as well as related links at the end of the first post. With an SWG you shouldn't need to add chlorine as frequently, though as I wrote if your chlorine demand is uneven either because you use the spa irregularly or the number of people in the spa varies, then you'll likely need to supplement with additional chlorine (such as with bleach).

CYA significantly reduces the active chlorine level so when the CYA gets too high then the oxidation and sanitation rates get too low and the water can get cloudy and the risk of getting hot tub itch/rash/lung increases (among other things).

[glennmacph]

thanks for the schooling on CYA,I bought a non-stabilizer chlorine for future shocking after the 30 ppm level is reached,

A water person tested my water and said your alk. is to low(50 ppm)it will damage your equipment and is bad for bathing too.I told her that its the only way to keep my PH balanced,and that my CH is at 100 ppm,they said its still bad to do

now what??????????????????????????????

[waterbear]

thanks for the schooling on CYA,I bought a non-stabilizer chlorine for future shocking after the 30 ppm level is reached,

A water person tested my water and said your alk. is to low(50 ppm)it will damage your equipment and is bad for bathing too.I told her that its the only way to keep my PH balanced,and that my CH is at 100 ppm,they said its still bad to do

now what??????????????????????????????

Ignore her. She really doesn't understand water chemistry. Ask her how low TA is bad for bathing. I bet she doesn't have an answer that holds water! (pun intended)

There is no evidence that low TA will damage equipment. If you are adding something acidic (such as MPS or stabilized chlorine) then it is possible for the pH to 'crash' and the low pH is potentially damaging. However, If you are monitoring your pH and TA regularly it is not a problem.

[chem geek]

What sort of non-stabilizer chlorine did you get? In solid form, there are only two. Cal-Hypo is calcium hypochlorite and will increase Calcium Hardness (CH) so is not something you want to use while lithium hypochlorite is fine to use but is very expensive. Clorox Regular 6% bleach is far less expensive, though is obviously a liquid so you need to be careful handling it.

As for low Total Alkalinity (TA), they don't know what they are talking about. It is low pH that can corrode metal, especially when combined with low pH buffering, but they are thinking of TA for two other purposes. One is to saturate the water with calcium carbonate, but that is to protect plaster surfaces, not acrylic spas (fiberglass can use some protection, but not usually as much). You will have raised your CH level to 120-150 ppm to prevent foaming and at hot (104ºF) spa temperatures 50 ppm TA (and 30 ppm CYA) with 150 ppm CH has a saturation index of -0.4 at a pH of 7.5 and a saturation index of -0.2 at a pH of 7.7. You don't want the saturation index to be too high or else you can get scaling in the heater that is even hotter (usually by 30 degrees or so which is about 0.2 higher in saturation index) and you want to avoid scaling in case the pH rises too much for whatever reason. You can raise your CH up to 150 ppm if you want to, but I wouldn't go any higher than that and if you don't have foaming at 100 ppm then that's OK to keep where it is.

The other reason for TA is as a pH buffer, but you already have two other pH buffers in the water -- 30 ppm CYA is also a pH buffer and 50 ppm Borates is also a pH buffer (I assume you've already added 50 ppm Borates such as by using ProTeam® Gentle Spa). In fact, at a pH of 7.5, the buffer capacity of 30 ppm CYA is the same as 36 ppm adjusted TA (TA reduced by 1/3rd CYA). The 50 ppm Borates has the same buffer capacity at a pH of 7.5 as 197 ppm adjusted TA (TA reduced by 1/3rd CYA and 1/10th borates). So with the borates, you have MORE pH buffering than even the high end of normal TA ranges typically recommended!

The higher TA levels are typically recommended because most chlorine and bromine sources that are used are net acidic, but unstabilized chlorine sources (i.e. hypochlorite) are close to pH neutral when accounting for chlorine usage/consumption. The pH rises when adding a hypochlorite source of chlorine and then drops again when the chlorine is used/consumed.