# Filter media



## StevenA (2 Feb 2008)

What can i put in my Fluval 205 external filter to help to soften the water to reduce the KH :?:


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## ceg4048 (2 Feb 2008)

Hi Tourney,
                    First, a clarification; The carbonate hardness of the water, kH, is not really related to water softness. The real measure of water softness is General Hardness (GH) which is a measure of the concentration of calcium and magnesium salts.

KH is actually a measure of the "Alkalinity" of water, meaning a measure of the concentration of carbonates and bicarbonates that affect the water's ability to resist a drop in the pH due to incursions by acids.

If it is water softness (GH) that you are trying to affect, then peat or peat granules can help to some extent.

The real question though is why you wish to reduce the kH or GH of your water. There are only a handful of plants that require low kH or low GH, and for the most part, plants tend to do better with higher kH and GH (or at least are not that affected by higher values)

If you have a good reason to want to lower the kH/GH (such as fish requirements) then it would be much better, as a general rule, to use a Reverse Osmosis unit and to cut your tap water with this RO output than to use additives.

Cheers,


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## Moss Man (2 Feb 2008)

You could try peat fibres or peat granules, various companies sell media like this, including Ehiem.


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## StevenA (2 Feb 2008)

Actually after making some enquiries, a friend of mine has got a reverse osmosis unit for sale, so i will be trying that. Basically i am trying to make the Co2 input more effective for my plants. I am still learning about the relationship between KH, Ph, and Co2, so please excuse any ideas or thought of mine that are incorrect, but I'm just trying to get a clearer idea about it all really. 

If i use the RO unit, should i use 100% RO water or a 50-50 mix with dechlorinated  tap water? And i assume with the RO water i do not need to use a product like Aquasafe, but obviously in the tap water i still do? :?


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## ceg4048 (2 Feb 2008)

Tourney said:
			
		

> Actually after making some enquiries, a friend of mine has got a reverse osmosis unit for sale, so i will be trying that. Basically i am trying to make the Co2 input more effective for my plants. I am still learning about the relationship between KH, Ph, and Co2, so please excuse any ideas or thought of mine that are incorrect, but I'm just trying to get a clearer idea about it all really.
> 
> If i use the RO unit, should i use 100% RO water or a 50-50 mix with dechlorinated  tap water? And i assume with the RO water i do not need to use a product like Aquasafe, but obviously in the tap water i still do? :?



Hi Tourney,
                  Nothing to excuse, really. That's how we all learned - by asking and reading. It all a bit complicated - chemistry, biology, fluid dynamics, construction...it's amazing!

You may want to check this post in the cookbook section to get a better handle on CO2 and it's measurement in the tank: http://www.ukaps.org/forum/viewtopic.php?t=467

Now, as regards the effectiveness of CO2, as you'll read in that post in the link above, CO2 has the same effectiveness and dissolves exactly the same regardless of the alkalinity of the water or of it's hardness. Therefore, you should not base your decision to use RO water on CO2 effectiveness at all.

Using RO adds a certain degree of difficulty to any tank, and life is complicated enough so you need to convince yourself that it is the direction you want to go in. Few here except for the hard core discus keeper or dwarf chiclid breeder bother with RO. There is no advantage whatsoever in terms of plant growth unless your tap water is from Lakes Malawi or Tanganyika, or unless your tap water contains high concentrations of toxic metals such as copper.

The ratio of RO-to-Tap would depend entirely on _why_ you are using it. As discussed above, if you wanted to grow one of the few types of plants that really require soft water you would mix RO to Tap in a ratio that gives you a result say, of kH 4 or lower and GH 7 or lower. It's impossible for me to say what ratio that equates to because I don't know what your tap water parameters are. The same story goes if you are keeping discus or dwarf chiclids and you want to keep the water hardness low. If you are using it for basic purification due to local toxicity (or bacteriological/viral reasons) then you would have to determine what ratio brings the mix to within safe levels for fauna.

Other than the Lake Malawi scenario, these are the only other basic reasons I can think of for using RO. Also, the more RO you use the more likely it is that you will have to add back calcium and other minerals to the water in order to avoid mineral deficiency in the plants  

Check the article in the link above and just ask if you need further clarification.

Cheers,


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## nickyc (4 Feb 2008)

I occasionally use RO to keep my hardness down in preparation for some discus.  I still put stresscoat in as RO does strip _everything_ out of your water and I've assumed that some of good stuff in stresscoat will help address the balance.  Others might say I've been wasting my time    but my LFS keeps telling me that RO in freshwater tank should be treated with caution


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## StevenA (5 Feb 2008)

Just tested the water straight out of my tap, and it has a KH of 15, and a GH of 19, HELP  

Do you think i have a good case to go down the RO route :?:

Or is there another way to soften the water, without major expense :?:


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## CJ Castle (5 Feb 2008)

> Just tested the water straight out of my tap, and it has a KH of 15, and a GH of 19, HELP



My water has a KH of 28+... However, I usually add 7:3 rainwater to tapwater, so that gives me around what I'm looking for... GH could be decreased a little (using various products on the market), but it's still fine...


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## StevenA (5 Feb 2008)

KH of 28+, wow that is high, i've seen posts on here and elsewhere referring to a KH of 7 as hard water, so i saw mine and thought the worst.


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## ceg4048 (5 Feb 2008)

Try the following experiment: Boil a pot of water for 10-15 minutes. Let it cool and re-test. Calcium and aother mineral deposits normally come out of solution as the water temperature increases. That's why limescale coats the heating element of your kettle, your washing machine and the hot water pipes. If you see a significant reduction in GH in the water after you boil it then you have a potential solution there, depending on how much your water change is. You could simply keep a reservoir and boil water throughout the week. That could get to be a drag though but it _is_ cheap. RO units typically have a 5:1 to 10:1 rejection rate so in order to collect 1 gallon of RO water you have to throw away 5 to 10 gallons (or use  the waste water to water your terrestrial plants or garden). This means a higher water bill.

Personally I would try growing the plants in tap and see what happens first before I resort to softening measures. See what happens first then change your process if you need to.

Cheers,


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