is tap water really that bad?

[Jeff]

since the topic of scientific studies is hot right now how about the subject of ro/di vs. tap water. the tap water here in s.a. is not really that bad and i know that everybody strives for 0 tds but what is really being tested as tds. is it calcium, phosphates, nitrates?
when i first started running a s/w tank i only used tap water for a year and i didn't have the algea problem that i do now that i'm using ro/di. i'm just curious as to what others have seen and want theere two cents worth.

[seamonkey2]

hmmmm, when I first set up my 75 and 125 I used tap water with the declorination drops, and had no algae problems either
now is all 0 tds

hmmmmm

jose

[Jeff]

go to saws.org and check out the stats on the water. they are not that high.

[RNall]

I have had 2 emergency situations that required fast filling of my 210 + sump. I used a giant trash can, tap water and dechlorinator both times.

I have seen no ill effects from it at all. As you, I have occasionally wondered if I'm wasting my time with the ro/di.

When I moved my tank from Houston, I called around to places near me asking if they sold ro/di or salt water. Surprisingly, they recommended tap water. I swear I thought they were kidding at first. Tap water? In a high dollar reef tank? How crazy and lazy is that?!?! Coming from multiple locations with horrid tap water, I assumed they did so because everything was in their tanks temporarily, it didn't cause that big of a problem for the critters in such a short period of time, the tap water was 'ok' and it's super cheap. I figured it would be really bad long term in a reef tank though...

In my previous locations and experience, using tap water would have been VERY bad. Like I said, I have used it multiple times here (a lot too) and even now it feels like I cheated....

I still wonder if I made a mistake. I really didn't have a choice at the time and everything looks good.

I continue to regularly use ro/di for water changes, dosing and top off though.

[jc]

I use tap water for my fowlr tank with no problems. I have even used it in my reef when I didn't have r/o water ready. Nothing bad ever happened.

[Bill S]

I didn't use RO/DI for a couple of years, and had nitrate problems. When I tested MY tap water (SAWS, north central), I had nitrates ranging from 10-15ppm. Pretty hard to keep it below 20 in the tank when you are starting at 10!

[Richard]

One of the problems some people have when they start using ro/di is that their alkalinity gets too low. So their ph gets low and some algaes do better in a lower ph. Low alk is never an issue with south texas aquifer water.

I use 50% well water and 50% di water sometimes when I don't have enough di water on hand. I don't have any nitrates in my well water and phosphate is really low too but the alkalinity is way too high for me to use it all the time.

[RNall]

I guess the smart thing to do is test it prior to use. I tested mine in both cases. There was a diffrerence in alk between the two tests though (about a month in between over the summer). If nitrates and phosphates are negligable (as they were in my case) and pH, alk and Ca in a good range, why not? Don't forget the dechlorinator though! It still feel like I cut corners though....:lol That's why I continue to use ro/di . There is probably a decent chance I'm wasting my time and money. Tap water (SAWS) is inconsistant though and I wouldn't add it withuot testing first....

[Jeff]

what i saw on saws .org was that nitrates ran from .094-2.46. now this will vary from time of year and how much water is in the aquifer, but i say thats not too bad. i like how this discussion is going lets keep it up. where's gary and his chemical analysis.

[RNall]

BTW, one of the LFS near me used ro unit prefilters on tap water prior to use.

[alton]

As the aquifer gets low the quality goes way down. Back in the 90's I did not do water changes in the summer months when the aquifer was down and I did not lose any fish to disease during those years. Now that Ro systems are better and the fact my water company gets the water from down south out of a sewage system and adds 4PPM chlorine, I have no choice but to use a good RO system, chlorine remover for my aquarium and filtered water for drinking.

[Ram_Puppy]

didn't i just read that part of the aquifer is contaminated with solvents? I think it's now on an EPA priority list...

I don't trust it for my gut, so I don't trust it in my tank.

<-- bottled water junkie.

[Bill S]

Just a little tiny part of the groundwater. The aquifer water is very, very safe.

[Ping]

Gary posted some info on this a while back. Mayby one of us can find it and put a link.

My first SW tank was a 100g fish only. 2 inch sandbed. No life rock. 2 emperor 400's. Small prism protien skimmer. No sump or fuge. NO aquariums bulbs. Tap water with 3 mos 5 gallon water changes. And no algae, cyno, no visual problems. I did kill a lot of fish though. I cant imagine how high my nitrates were. "Hey guys, lets see how many goldfish my lion can eat."

[GaryP]

There are basically teo problems with using tap water. First is that yourr artifical salt is formulated to be used with RO. I know youa re thinking the same as me. Why throw out the baby with the bath water? Meaning why throw out the calcum and alkalinity that is naturally present in tap water. Well, it can cause the calcium and alkalinity to exceed its solubility limits and cause CaCO3 to precipitate out in the trash can. I think SAWS water is around 80 ppm calcium and 175 alkalinity. I think that's about double the alkalinity of SW. You can get into an imbalance situation, as Richard noted, with alkalinity that high.

As for evaporation replacement (make up water), you are essentially replacing pure (evaporative) water with a high TDS water. This is sorta like (but on a smaller scale) as using SW for top off. Then, on the other side, we are doing exactly the same thing by dosing additives. In the case of additives though, we are theoretically only adding those compounds (mainly calcium and alkalinity) that are being removed by biological activity.

There is chlorohydrocarbon contamination in the aquifer, mainly from dry cleaning establishments. However, the levels are very low and well below the levels allowed by the Safe Drinking Water Act (SDWA). Ram, do you recall when Perrier was contaminated with benzene, a carcinogen? For those that trust bottled water because its more healthy, go ahead. Most of what you are getting is probably coming from the aquifer anyway after being carbon filtered. Carbon filtration is notorious for introducing a lot of bacteria into the water being filtered. Are these bacteria dangerous? Probably not. I just have a hard time with idea that water from a bottle is somehow better then tap water, especially water from the Edwards which is one of the best water supplies in the US. It sure beats drinking Mississippi River water like when we lived in New Orleans.

Bill, if you are tryly getting those kind of nitrate levels in your water, I would be screaming bloody hell. I believe 10 ppm is the max level allowed for nitrates by the SDWA. It also means that your water is contaminated with sewage. I think that analytical error may be a better explanation. When in doubt, take a sample to SAWS and have them run a kjedhal analysis (total nitrogen) on it.

My conclusions on this? I can see pros and cons on both sides of this question. I used Edwards tap water for years and didn't really start using RO until I moved away and lived in industrial areas where the local water supply was coming from surface water of questionable quality.

[Jeff]

so if your alk is way low would it not be a good idea to do a water change with tap water?

[Bill S]

When purchasing your bottled water, look for the source. I think it was Ozarka that said: "Houston municiple water".

[LoneStar]

Penn and Teller talked about bottled water on their Showtime show 'Bullsh*t'. It was funny to see the dilusion of what people paid out of pocket for plain old water. Heck they even made fun of Glacier bottled water which is bottled straight from the faucet down in good 'ol Corpus Christi Texas. From their video, it looks like it was filmed by the Pepsi Cola distribution plant off of SPID.

[GaryP]

so if your alk is way low would it not be a good idea to do a water change with tap water?
Personally, I don't think that water changes are a good way to manage alkalinity. Some critters, notably crustaceans, are sensitive to rapid alkalinity changes. Its sort like dumping a new purchase into the tank without acclimating. I'd rather see you adjust the alkalinity slowly with a supplement before doing the water change. Besides, let's do the math.

Assume tank alkalinity is 6 DKH and water change water is 10 and you are doing a 20% water change. The resulting DKH would result something like this:

(80% X 6) + (20% X 10) = 4.8 + 2 = 6.8 DKH

You are still low. As I said above, it's not a very good, or effective, way of managing alkalinity. Ace, do you think you can get me a job teaching chemistry? I have the dilution equations down pat.

[GaryP]

There are some brands that say San Antonio municipal water supply. To be honest, they do more then just bottle tap water. Some are simply carbon filtered to remove any organic contaminants. As I said before, there isn't much to start with and carbon is not very effective for chloro organics. The higher end water companies take well water and convert it into RO and then add the minerals back that give it its characteristic taste; mainly calcium, magnesium, and manganese.

[Flobex]

i have a question... We have a water softner system at my house, so woul my tap be ok? i use alot of dechlorinater, and i know its just fine in the FW tanks, (has been for years) but i dont have anything to test it with...

[GaryP]

Softened water is soft because the calcium and magnesium are taken out and replaced by sodium. The alkalinity is still there. Its really a question of why bother? It doesn't have the benefits of tap or RO water. It should be OK for top off, but I wouldn't use it for water changes.

[Flobex]

So it was a pretty bad move i my part, when i just filled my tank with soft water, and salt... will it be ok, if i just for the cycle, leave in this water, and as i do water changes, use ro water, to eventually get it all out?

i could just calcium, and other things i need for now...

[GaryP]

I wouldn't panic over it. As long as your levels are OK I wouldn't sweat it. I didn't mean to imply that using soft water is bad. Its just not as good as other alternatives.

[Richard]

The biggest problem you might have using softened water, especially for top off, is that you will drive your salinity up over time because of the extra sodium in the water.

If you are using potassium instead of sodium in your softener then you might have more algae problems since you will be adding potassium everytime you top off. It's another nutrient for algaes.

[Flobex]

we add salt... i will stop using the softwater... i just got a bug, and i filled it up :P thanks.

[GaryP]

The biggest problem you might have using softened water, especially for top off, is that you will drive your salinity up over time because of the extra sodium in the water.

If you are using potassium instead of sodium in your softener then you might have more algae problems since you will be adding potassium everytime you top off. It's another nutrient for algaes.
Richard, I'm not quite sure what you are referring to. Sodium replaces calcium and magnesium at a 1:1 ratio in a softening resin so there should be no more increase in salinity then there is with tap mater.

Potassium is a nutrient for algae? I would hardly call it a limiting nutrient since there is almost 400 ppm in NSW.

[Bill S]

Yes, seawater is mostly sodium chloride and potassium chloride.

[Richard]

Richard, I'm not quite sure what you are referring to. Sodium replaces calcium and magnesium at a 1:1 ratio in a softening resin so there should be no more increase in salinity then there is with tap mater.

Potassium is a nutrient for algae? I would hardly call it a limiting nutrient since there is almost 400 ppm in NSW.


Yes calcium and mag are replaced by sodium. So you you topoff, water evaporates sodiom does not. Repeat repeat repeat repeat....sg goes up. Critters aren't going to use up the excess sodium to my knowledge. Like they would ca or mg.

Potassium is used in fertilizers as a nutrient so that continually adding more could have an effect on algae growth. Please note I did say "might".

[Bill S]

Potassium & Calcium are in approximately equal quantities in natural seawater. About 400ppm. Sodium, on the other hand, is around 19,000ppm.

[GaryP]

Yes calcium and mag are replaced by sodium. So you you topoff, water evaporates sodiom does not. Repeat repeat repeat repeat....sg goes up.
OK, you are absolutely correct. I'm sorry, I misunderstood your comment. I thought you were saying that softened water was worse then tap water. Pretty much the same without the benefit of the calcium and magnesium.

[Richard]

That is the same type of thing I'm talking about when I tell people they can drive their alkalinity too high by always topping off with tap water.

I had a guy who was losing his african cichlids from having auto topoff on his sump hooked up to tap water. After going through 3 cc's of the salifert reagent without a color change I gave up trying to measure his alk and just told him he need an ro unit for his auto topoff. That is the first and only time I've ever seen or even heard of anyone having alk too high for african cichlids.

Of course the carbonates are used up faster in a reef than a fw tank but if you lose 4-5 gallons per day like my tank and and your carbonate demand isn't real high then the same type of thing could happen.