help high alkaline reading

[chris9911]

I have a problem with high alkaline reading. My test kits are reading 8!! I used two different test kits to confirm this. My calcium zone is 1 as a reasult of this alkaline reading. How do I lower the reading? My ph reading looks fine at 8.3

[Randy Holmes-Farley]

8 meq/L or 8 dKH?

[chris9911]

8meq/L

[Randy Holmes-Farley]

My suggestion is to maintain calcium at about 3-4 meq/L using calcium chloride and the alkalinity will come down on its own.

How to do that is detailed in the article that shows the zones:

Solving Calcium and Alkalinity Problems
http://www.advancedaquarist.com/issues/nov2002/chem.htm

[chris9911]

I read the article and I think the article assumes the ro water has lower alkalinity than the fish tank, which isn't the case with me. My r.o. water also has 8meq/L of alkalinity. I'm using kent bare bone r.o. system.

[Randy Holmes-Farley]

What seems rather unusual. What is the alkalinity of the tap water? What kit are you using?

[chris9911]

I use Red Sea brand and fast test by aquarium systems. My tap water comes from a well.

[Randy Holmes-Farley]

Bicarbonate should be about 90% rejected. That would put the well water at about 80 meq/l alkalinity. That sounds almost unbelievably high.

Still, if you want to lower alkalinity in the aquarium by precipitation of calcium carbonate, that is one route. Just add clacium chloride over time and the alkalinity should decline.

Another is to add calcium chloride to the RO water itself, and let the solids settle before using it.

What is the calcium level in the aquarium? It is very likely to be low if alkalinity is 8 meq/L.

[chris9911]

I called the water company and they told me alkalinity of the well is about 6meq/L

[chris9911]

so I guess something happened along the way from the well to my house that increased the alkalinity.

[Randy Holmes-Farley]

The post RO water shouldn't be 8 meq/l then. It ought to be much lower. Are you adding anything to the water before or after the RO?

[chris9911]

No, I'm not adding anything before or after the ro. I will go home and measure the alkalinity of my tap water.

[Habib]

With RO units there is the waste line and the RO water line.

Is there a possibility that you are using the waste water?

Measuring alk of both lines might tell which line is which.

Another possibility is also that the membrane is leaking.

[gtrestoration]

I have a related question...

What should the pH of RO/DI water be if the TDS reading shows 0 (and assuming that it's correct)?

You stated bicarbonate rejection by the RO should be about 90% and I assume then the DI would remove the balance. So then the pH would be 7.0?

Thanks... Steve U

Steve U

[Randy Holmes-Farley]

You might be right, Habib, especially the part about the membrane leaking.

Do you have any way to see if the RO is taking out anything? A TDS or conductivity meter?

The pH is not a suitable way to judge an RO membrane. pH meters and kits do not work well in purified water, and what traces do get through an RO will skew the pH in either direction. My RO/DI water reads a ph about 10, even though it is good DI water. Is that real? I do not know.

[gtrestoration]

pH meters and kits do not work well in purified water, and what traces do get through an RO will skew the pH in either direction. My RO/DI water reads a ph about 10, even though it is good DI water.

That's where I was going with this, the pH of my RO/DI is always real high (as in 9-10) if I use the Pinpoint to read it. Same as the conductivity meter, always says that there is something left in the water, so I don't use it anymore. The DI cartridges I use are color changing and I also really ignore them.

The truth lies in the tank, and at about 5 gallons per day in evaporation it doesn't take long to know that something is feeding the algae.:eek2:

Thanks again Randy,
Steve U

[Randy Holmes-Farley]

A conductivity meter is a much better way to judge what is coming out of an RO/DI.

What kind of reading do you get?

[chris9911]

Habib, you were absolutely correct!! I bought my ro unit from a garage sale and the seller gave me wrong information. He told me blue line was waste and orange was good, when it should of been the other way around. I can't beleive my corals didn't show any signs of problem when I was using the bad water. Thanks

[gtrestoration]

Randy,

I changed everything (not RO) about a month ago because the TDS read 2. After changing 2 sediment, 1 carbon and the DI cartridges it still read 2 after 10 gallons. So I don't think it's correct. My next plan is to add a satellite DI cartridge.

City tap water can read as high as 700 and very hard.

In my FW days, this was a real pain, trying to buffer down for Discus was near impossible. At that time RO/DI units were not as inexpensive, relatively speaking.


Chris9911...

That's to funny, at least the carbon would have been removing some of the impurities even from the waste water. I drag 200' of waste line around my back yard to water veggies and trees.

Steve U

[Randy Holmes-Farley]

Another DI cartridge would likely work, and isn't wasting anything as it will only very slowly be used up, but may not be necessary.