PlanetCatfish.com

Hi guys,

Firstly happy new year and many thanks for all your help last year. Rarely do you get such a helpful and knowledgable bunch of people all pulling in one direction. So cheers!

Anyhoooo....

I'm thinking of getting an RO filter but I want to make sure I get the right measurement device and also need a bit of help on the different measurent yardsticks.

Firstly with a handheld TDS meter can you also measure conductivity?

I know about PH nitrate nitrate ammonia but how is hardness measured? Is this TDS ppm?

Also how can I measure conductivity and what is good bad or is it like ph? Some fish like high, some like low?

I've seen (i may be wrong on the denotion) Kh and Gk or Gh perhaps?

Can someone help me or point me in the right direction?

My tanks are mainly Amazon catfish but I also have 3 syno's.

Hey, have a read of this article. It should answer several of your questions.

Firstly with a handheld TDS meter can you also measure conductivity?

Conductivity is actually what they measure to be exact. They give you a rough guide to TDS by dividing conductivity by two.

how is hardness measured? Is this TDS ppm?

Hardness is no single thing, like ammonia. Rather it's a term for all dissolved minerals, but in particular the common ones such as calcium, magnesium, sodium, potassium etc which make up the bulk - but there are hundreds of others. Some minerals contribute more to conductivity than others, but yes, without sophisticated equipment, measuring TDS with conductivity gives a very close idea of hardness (total mineral concentration).

Also how can I measure conductivity and what is good bad or is it like ph? Some fish like high, some like low?

Yup.

I've seen (i may be wrong on the denotion) Kh and Gk or Gh perhaps?

KH refers to the component of minerals that change pH and make water more alkaline (e.g. carbonates).

GH usually refers to the parts that don't, commonly calcium and magnesium.

I'm thinking of getting an RO filter

Before you spend the money, decide whether you really need one, as they waste a huge amount of water. Not good if you are on a water meter...

I would only consider one if I were keeping ultra-low pH blackwater fishes. Most other fishes are fine in all but the hardest tapwater.

High nitrates and phosphates on the other hand are difficult to remove from tapwater, and together with hard water, make an RO seem like a better proposition.

So, you really need to ask yourself:

1) what fish am I keeping, and do they really need softer water?
2) what are the specific values of my tapwater, in regard to conductivity, KH and nitrates (these two are best measured with a chemical test kit)?

With answers to these two questions we'll be better placed to offer more advice.

A fantastic reply.
Spot on

racoll wrote:

how is hardness measured? Is this TDS ppm?

Hardness is no single thing, like ammonia. Rather it's a term for all dissolved minerals, but in particular the common ones such as calcium, magnesium, sodium, potassium etc which make up the bulk - but there are hundreds of others. Some minerals contribute more to conductivity than others, but yes, without sophisticated equipment, measuring TDS with conductivity gives a very close idea of hardness (total mineral concentration).

I believe that this should read "TDS is not a single thing". Hardness salts/minerals is defined as "multivalent cations", so sodium and potassium are not counted as hardness.

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Mats

One aspect of RO water that usually gets overlooked, or at least I did for the first half year of using it, is that the waste water is actually clean filtered tap water. For most RO units, there are 3 filter cartridges before the RO membrane. The unit I use has a 10 micron sediment filter for the first cartridge, a 5 micron carbon cartridge for the 2nd and a 1 micron carbon cartridge for the third. The waste water is filtered and can be used for most grow-out purposes if your pH isn't too high or low.

This is the unit I use http://www.airwaterice.com/c=PyCw5dQV6Y ... 5-GPD.html

Spot on
The waste water is described as Rejected water and is far better than tap water.
the word waste water is used because few people know how an RO Unit works.

I'm trying to breed corydora's trilineatus - One of them looks fatter than most but shows no sign of laying any eggs - I've heard that RO water may help them spawn but this is coming from the US where Chloramines are added to the water. I'm in the UK with a PH around 7.8. I change the water regularly with water that makes the temp go down by around 2 degrees.

It may help, but it's often hard to say for certain what helps and what doesn't unless you keep two lots of the same species and do the same things to both group, except for ONE thing - say you start using RO water, and they breed. You can't say for sure that the RO water was what made them breed. They may just as well have bred ANYWAYS, because the time of year, weather systems (e.g. low pressure), or some other.

I don't see any reason not to try using RO water, I just don't want people to say "I did X, and Y happened, therefore X causes Y to happen" without proper proof - and the only way to achieve that is to have two identical setups, and then try X on one them, and see if Y only happens in the one that you do X on (and ideally, more than once!).

It is true that many corys (and other fish) breed in the rainy season, which also gives softer water and lower temperature. RO water is softer than your tap-water (certainly if you have pH 7..

Also, I would ignore differences between chlorine and chloramine - a good water conditioner works on both, so that shouldn't be a reason.

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Mats

I previously posted that the waste water from a RO unit can be used because it had pasted through 3 stages of filtration before it hit the RO. Although this is true that it is filtered I would have to expound on this part to clarify things so that i don't mislead anyone. After I posted, I received an expansion kit, to turn my 75gal/day into a 150gal/day unit, and so was able to examine the path the water took through the RO membrane and verified that although the water going into the RO housing is filtered, the waste water is not the same cleaned water. As the water is forced through the RO membrane whatever contaminants, chemicals, and minerals is trapped by the many layers of the membrane. It is "pressed" from the outside of the housing towards the center. The water that exits the center is RO water. The problem is that the membrane doesn't catch and hold the impurities in place. Some of it gets flushed lose by the waste water that exits. But there still is a way to utilize this water without pouring it down the drain. A post filter can be installed on the waste water output and this will catch any remaining contaminants. I try not to waste any water because I have to pay for it.

Obviously, if 5 units (liters, gallons) of water go in, resulting in 1 unit of RO weater and 4 units of waste water - the wate water will have increased its hardness 1.25 times

Because 4 * 1,25 + 0 = 5 and 5 hardness went in

For unwanted minerals, phosphate, nitrate, copper et cetera, the same goes. So in areas where the tap water is rich in these stuff, the waste water is better not used - or to flush toilets

In areas where the water is good, but too hard, the waste water can be used for anything. For keeping hard(er) water fish or for human consumption. Calcium and magnesium are good minerals, used to build bones, and therefore hard water is beneficial for ones health

Bear in mind also that the carbon should hold things like lead, copper and pesticides, as well as chlorine. So, yes, the waste-water isn't clean water like the RO water - the whole principle of an RO unit is that the pure water is squeezed through the membrane by the pressure in the water, and other stuff stays behind on the "dirty" side of the membrane. So yes, the "dirt" will be more concentrated in the waste-water.

I ran 4 of my tanks on pure waste-water for some time - it was for fish that is "less sensitive" types. But since the RO unit would produce a tankful of water or more every day, the four tanks would have their water replacced a couple of times every week, so no hug buildup of nitrate, etc.

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Mats

Well I bought some RO water and have done some water changes....no eggs since the initial spawn....I'm going to take notes and see what happens.

I think maybe the live food was a good trigger...they spawned initially without RO water so I surely can replicate that!