Liquid bleach vs. Total Dissolved Solids?

[CarlD]

TDS has been around for a long time and is usually the reason given for a pool getting algae outbreaks that can't be controlled because of the 'old water' with high TDS. Of course, the CYA level that is through the roof because of the use of stabilized chlorine has nothing to do with it at all!

Nah, nothing at all--until they say "Oh! You have chlorine lock!" (whatever THAT is--another Never,Never Land term).

[socalKC]

No one has applied scare tactics on me, I have no algae out break, nor old water.....I just wanted to know. Maybe not a question that can be answered here... sorry, thought this was the place to ask. my mistake. thanks anyhoo.

K

[chem geek]

socalKC,

Please don't be scared away by the sarcasm. The "TDS is bad" line is just common. You wanted information and the answer is that you do not need to worry about the TDS level, but you do need to make sure that your salt level (which really measures chlorides and reports it as ppm sodium chloride) is in the range that your SWG requires (varies by mfg. but usually around 3000-3500 ppm or so).

In a plaster/gunite pool with 100 ppm TA, 300 ppm CH and 30 ppm CYA, then the TDS will be at least 185 ppm above the salt level. Usually, it won't be much higher than that because the main component of TDS is salt.

Richard

[waterbear]

The thing we have been trying to say is that the pool industry has blamed TDS for problems in pools that have nothing to do with TDS. I suspect part of that is from the chemical companies that manufacture trichlor because if the word got out that their stabilized chlorine caused the problems in pools it would hurt their sales so they use TDS instead. Bottom line, if you have old water your TDS will be higher than if you have new water. This in itself does not cause problems but if trichlor was used there will also be very high levels of cyanuric acid and that WILL cause problems. If they blame the cyanuric acid it would hurt their sales. The cure for high TDS and high CYA is the same, however...drain and refill!
Don't worry about TDS is all we are trying to say.

[CarlD]

No one has applied scare tactics on me, I have no algae out break, nor old water.....I just wanted to know. Maybe not a question that can be answered here... sorry, thought this was the place to ask. my mistake. thanks anyhoo.

K

Socal, you have us all wrong. We have all seen SO many scams, have had SO many honest but ill-informed pool owners come here and relate the layers of nonsense that they have been fed by pool stores, that I coined the phrase "Pool-Stored" a few years ago for victims who had their pockets picked.

We don't sneer at people who have been pool-stored, we empathize with them. Most of us have been there. And the weapon to fight back against it with is information and knowledge.

If you haven't been taken or scammed by them, that's really great! You are wisely skeptical enough to protect yourself. That's EXACTLY what we encourage you and all the rest of us to be.

TDS is one of their favorite scare-tactics. I had a guy give the whole song-and-dance a couple of months ago about liquid chlorine adding TDS.

Now LC (bleach) adds a particular TDS--Salt. But years and years of LC use won't add NEARLY as much salt as what is required for a Salt Water Generator. A SWG pool has TDS levels that would make a pool store guy positively DROOL at the prospect. But it's all nonsense--Salt as a TDS is basically harmless until there is SO much that the SWG shuts down.

Phosphates are their other big scam so they can sell phosphate reducer. Lately they even are selling phosphate reduction maintenance plans (like you have with your HVAC guys)!

We have found that simply following good, simple maintenance practices consistently works for pretty most everyone. One in a thousand gets into trouble with TDS or phosphates.

[dipper]

would filling your pool through a water softener give you sky high TDS #'s???
would it be better to bypass the softener and then worry about getting rid of the iron in the fill water? Just wondering what the best route to take would be. Thanks, Eddie

[chem geek]

A water softener is just going to exchange one set of ions, such as iron, copper, calcium and magnesium, with another set of ions that are more inert, such as sodium or potassium. Though this technically changes the TDS number due to the differing molecular weights of these substances, in practical terms this doesn't matter.

It's not TDS itself that is any problem, but rather what specifically TDS is composed of that could be an issue. If the TDS is mostly plain salt (e.g. sodium chloride), then this isn't a problem (in terms of corrosion) unless it gets really high, and remember that SWG pools have around 3000 ppm salt. If the TDS is composed of a lot of dissolved organic compounds, then some of these may cause side effects though most do not -- remember that Cyanuric Acid (CYA) is an organic dissolved solid and it affects chlorine effectiveness.

The main thing that filling a pool with water from a water softener does is to add water that is depleted in calcium and is therefore lower in Calcium Hardness (CH). Depending on the type of pool you have, you want some CH (i.e. plaster pools typically have around 250-300 ppm CH). So if you are using the water softener to reduce the iron content of the fill water, you will probably have to supplement the water with additional calcium chloride to raise the CH. That's perfectly fine to do.

Richard

[dipper]

Thanks for the response and the explanation. I am always thinking of different ways to manage my water chemistry to make it easier for me. Without the proper knowledge, I get me nervous if I don't fully understand what I am doing and the consequences that can happen. I would hate to mess something up. Thanks again, Eddie

[CarlD]

Richard,
You've posted a lot of amazing posts here over the last couple of years but the one above may well be your best. I don't think I've ever seen you write better or more clearly and concisely. It combines the perfect blend of scientific knowledge and nuts-and-bolts techniques!

Wow!

Carl