Conductivity

[jafo]

I have read much about water hardness (Gh,Kh, DH, buffering, etc.) and no longer use any chemicals to alter anything. My tap water is very hard and has a Ph of 8.2+. I have gotten an r/o unit and a conductivity meter as I want to get more into breeding and not just keeping Apistos. I have been doing water changes with the r/o water for a couple months now and have soft and to very soft water depending upon the tank. From what I've been reading here many of you say that conductivity is what you check but not what numbers you look for. I have already had A. nijsenni, A. cacatuoides, and my Angelfish spawn a couple times over the last month or so ago but didn't have my meter then. None of my current Apistos are wild and I know that does make a difference. My r/o water is around 75uS and a pH of abt 7. Right now conductivity in my tanks are mid 90s. My current Apistos are: agassizii, cacatuoides, nijsseni, trifasciata, viejita. I'm looking for a range to shoot for.

 

[tjudy]

Is the RO water out of your machine 75mS, or is that the conductivity in the tanks you have been adding RO water to?

75 mS is pretty good for most apistos. Some do not need it that low. If that is the conductivity of the RO water itself, then the RO unit may not be doing as good a job as it should.

 

[jafo]

That is out of the r/o unit. Most of the tanks have water in the mid 90s.

 

[tjudy]

In any case a conductivity of less than 200 uS (approximately 100 ppm) is fine for most soft water apistos. Only the really tough nuts to crack, like A. diplo, would need it softer. For what you are working with the that level is fine.

 

[jafo]

Thank Ted. Checked my tap water and r/o water last night using my test kits and the tap was 22 deg and r/o 4. Nothing but limestone around here for the most part

 

[tjudy]

What is the conductivity of the tap water? Do you use a water softener for the house? If so, use softened water through the RO. You will get RO water with lower conductivity and extend the life of your membrane.

 

[jafo]

Best I can recall it's low 170s. I'm at work now and can't check it lol. I don't have a water softener and I know I'll go through membranes more often than most with my tap water. I had a different meter a few weeks ago and still waiting on it to be repaired. It did show lower numbers than the one I am using right now. I went back through my notes last night and the r/o water was around 50mS with tds of low 30s. I like to know what changes with my parameters so I am a packrat with test results

 

[tjudy]

I suspect that your tap's conductivity is a lot higher than 170. Sometimes a meter will use a symbol to denote a multiplier for high values. My meter flashes a little 'x10' next to the reading value to tell me to multiply the number by ten.

If you tap water really is only 170 uS, then RO with 50 uS means that the RO unit is only rejecting 70% of the tds. If the tap is really closer to 1700 uS, then the unit is rejecting 97%, which is a lot more reasonable.

 

[jafo]

Unfortunately the meter doesn't have an indication of what scale it's on and I hadn't even thought of that. I do know that the water here fluctuates big time. I have gotten water from the r/o unit as high as as 100 mS and this morning before work it was 83.5. It changes by the hour. I've dumped more than a few buckets :frown: when all my drinking water jugs were full.

Thanks Ted you have helped me a lot

 

[dw1305]

Hi all,
Jaffo you need to calibrate your meter with a standard. You can use KCl (potassium chloride) which you can buy widely as "sodium free salt".

The calibration solution is 0.745g of KCl in 1 litre (1000 ml) of R.O water, which has a conductivity of 1411microS at 25oC. This solution is fairly stable and will keep for at least a year. You can dilute it down 1:10 to give 141 microS, but that wont keep longer than a couple of days. As your R.O water seems to have a high conductivity all ready I'd buy distilled water rather than using your R.O. for making the standard.

If you haven't got scales accurate enough for 0.745g use 7.45g and dilute that solution 1:10 to give you 1411 microS.

cheers Darrel

 

[jafo]

Thanks Darrel I'll give it a try

 

[wethumbs]

Just an idea

You should also collect rain water from the gutter downspouts. I used to live in MN and they have 'liquid rock' there as well. I used a RO unit in conjunction with a water softener. It is also a good idea to 'soften' the water for regular use as it will prolong the life of your water heater. I was able to get RO water less than 10uS. The major downside of owning a water softener was hauling 1000lb of salt each time I go shopping (I like to stock up when they were on sale).

You can also purchase conductivity calibration fluid from Pinpoint. $7 for a bottle of 45.0uS standard fluid.

 

[jafo]

May be able to rig something up but not gonna use my downspouts lol. Too old and rusty :frown:

 

[dw1305]

Hi all,
Wethumbs wrote "You should also collect rain water from the gutter downspouts."

I use rainwater as well. The tap water here is low in polllutants but quite hard (about 650 - 800 microS), mainly because it's all limestone locally (Jurassic limestone and clays), and the chalk is only about 10 miles to the S. (Salisbury Plain) and E. (Pewsey Downs).

Jafo wrote: "not gonna use my downspouts lol. too old and rusty".
I wouldn't worry too much about the rust, you can run the water through a sponge, or floss, to filter the particles out, and filter it through carbon if your worried about organic pollutants.

We are lucky is we get a lot of rain all throughout the year, the oly down side to using rainwater is that you may find your rainwater isn't as low in conductivity as you would expect, as it will pick up calcareous dust from roofs and the atmosphere.

At the moment the rainwater in the water butt is about 50microS, and the rain falling down to about 10microS (pretty much the same as out of a steam distillation unit), but in the summer the rain can be well over 100microS.

cheers Darrel

 

[jafo]

Started mixing some distilled water this week but rain is coming May try to rig something up this evening and fill a few buckets

 

[Mike Wise]

If possible, it is always best to wait for 15 minutes or so after it starts raining to start collecting water. This allows dust and dirt to be washed out of the atmosphere, roof, and gutter system.

 

[jafo]

Been taking the top 4" of snow off the 7" I got last night and melting it down on the stove. Getting great numbers now

 

[Apistomaster]

1700 microseimens/cu cm sound more likely for your tap water.
I use the TDS setting on my meter just because it is easier to remember old readings for a guy who doesn't take notes.

You should get at least a 95 to 97% reduction in the product water regardless of units used to measure. More if you use a post-RO mixed bed ion exchange resin cartridge. I don't use mine. It gets down so low that more is not necessary. Ball park numbers are sufficient for fish breeding anyway.

I took my EC/TDS meter along with me to test the water of one of my favorite trout fly fishing rivers in northern Idaho last September; minimum flows of the year. I was amazed that the TDS was only 15 ppm. I knew the river was not considered to be "rich" or "productive"; the best trout streams are quite high in dissolved calcium carbonate, but this stream is like Cardinal Tetra water. The pH was 5.1. Most "good" trout streams will be 7.6 to 8.4 pH range. Little wonder it takes 6 years for these native West Slope Cutthroat Trout to reach 16" in Idaho's Lochsa River.
What I wouldn't give to have that water trucked in as needed from a 140 miles away. My city water runs 340 ppm TDS at a pH of 7.4 which isn't all that bad for most general fish keeping.

 

[jafo]

Thanks. Got my meter calibrated and the numbers look much better now They are all in the low 60s to upper 50s uS and 30-34 tds.