TDS Conversion and pH Questions - The Planted Tank Forum
 
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post #1 of 7 (permalink) Old 03-05-2005, 07:34 PM Thread Starter
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TDS Conversion and pH Questions

Well, i tried to search the net and it didn't seem to work so could someone help me or provide a link for me to read up on.

I have a conductivity meter (i believe it measures TDS in micro siemens) is it possible to use this via a conversion factor/formula to convert to kH so I can compare it with my pH to get how much CO2 in ppm I'm injecting into my tank?

or a close approximation or do they measure totally different things (or close enough so I can use the pH kH chart to determine the [] of CO2 in my tank? (conductivity meter is left over from a friend and I just calibrated it)

and I was playing with a pH meter, just calibrated it,
during the day the pH is around 6.4 (in my tank) at night with the airstone running it's 7.1

I'm trying to determine if there's a problem with this fluctuation, 6.4 to 7.1 is quite a big jump (in relative terms of concentration) or is it normal to see this much pH swing in a tank between daytime and night time (due to plants using CO2?)

I haven't seen the fluctuations without the airstone running at night though (the reason i'm running my airstone is I recently increased my bubble count of my CO2 and trying to do the 'looking at my tank's reaction analysis' to see if the co2 level affects my fish and don't want them to look like they're suffocating and gasping for air near the top of the tank)


if this topic has been discussed on here before please send me the link so I can read up on it

thank-you for looking at my questions
it's pretty simple stuff (which I'm assuming has been discussed but I can't really find it) so pls be patient and nice or e-mail privately [email protected] if you have anything non nice to sat =)


Raymond


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post #2 of 7 (permalink) Old 03-05-2005, 09:47 PM
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Quote:
Originally Posted by rwong2k
6.4 to 7.1 is quite a big jump (in relative terms of concentration) or is it normal to see this much pH swing in a tank between daytime and night time (due to plants using CO2?)
Running the air stone will cause surface agitation and lose you CO2 (causing a ph increase). This would be the reason for the increase in pH as usually you would expect to see the ph decrease slightly at night as plants do not utilise the excess CO2.

With my CO2 on constantly (24/7), I only see a pH difference of 6.99 to 6.93 over night, but then I have a good KH of 11.5dGH

A TDS meter measures "Total Dissolved Solids" in the water, which is a total figure for every solid substance dissolved in the measured amount of water. The measure of KH as CaCO[size]3[/size] will indeed be one of these but there is no way to isolate it from the total result obtained unfortunately.

HTH


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post #3 of 7 (permalink) Old 03-05-2005, 10:10 PM Thread Starter
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stu, how much co2 (ppm) are you running on your tank? and do you have the specs for your tank?
opps just read your signature,

I'm trying to figure out how much 'more' co2 i can put into my tank without hurting the fish but help the plants

and trying to see if i can save some $ without buying a hardness test kit, my tap water was around 1~2 kH last time i tested it (a while ago) and it goes softer when the snow/ice mets from the mountains

so I do add CaCO3 + MgSO4 to my tank regularly but just started this dosing schedule that looks like 'wolf...'

but honestly I'm just using the 'look at how my plants are reacting method'

Raymond


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post #4 of 7 (permalink) Old 03-06-2005, 09:22 AM
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Quote:
Originally Posted by rwong2k
stu, how much co2 (ppm) are you running on your tank? and do you have the specs for your tank?
opps just read your signature,

I'm trying to figure out how much 'more' co2 i can put into my tank without hurting the fish but help the plants
At the start of the day (i.e, what has built up over night), levels are at approx 33ppm and this dips to about 30ppm at the end of the day due to utilisation by the plants. (These levels are auto-calculated for me by Aquarix software. By using Chuck's calculator I get higher readings, but since you can only enter values of pH and KH to 0.1 and not 0.01 accuracy, I go with Aquarix - might be wrong!)

To be honest, it's not easy to say what is an "acceptable" level as different experiences have occured with different people. Some run around 40ppm, some have seen no problems with 50ppm, I read a source somewhere that fish will tollerate up to 100's of ppm of CO2! However, I would say that you have to take into account the species of fish exposed to the levels. Also, fish stock level, planting density, plant species, etc, etc..... again, hard to say definitively!

If you want to try more CO2, the key is to trial it carefully, upping by small amounts, then monitoring fish (and plant) health before going for the next upping. Be aware of the nighttime increase though..... if you run close to the limit for fish during the day, you might not realise the toxicity of the level from the increase at night until it's too late.

HTH


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post #5 of 7 (permalink) Old 03-06-2005, 09:37 AM Thread Starter
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Possible to determine CO2 levels /w pH meter and conductivity meter only?

Hello Stu,
thx for the input, I'll keep careful watch over my fish while I'm playing with increasing the CO2 level,

I guess the main question I'd like to ask in determining the CO2 levels in my tank is, is it possible to get a PPM level of CO2 with a pH meter and a conductivity that measures TDS in microsiemens?

thx
Raymond

and some more comments about my personal experience:

i've increased my bubble count of my co2 and made my reactor/difussor combo into something more effective/efficient (or so I think) the plants are greowing pretty crazy although I do keep pretty easy to keep plants:

+ i've added the elite mini powerhead/subfilter into the bottom of my tank for more circulation, I currently only have some BBA on my equipment and lower leaves otherwise everything seems healthy,

oh and i've recently started a dosing schedule like wolfy's and waiting for my gregwatson.com order to come in with some missing stuff (mainly phosphate but a little worried and have to be careful dosing this)

my plant list
Altenanthera neineckii 'roseafolia'
Anubias barteri 'coffeefolia'
Bacopa (carolinia or monnieri) it's the bigger leaf one i forgot i think it's carolinia
glossostigma elatinoides
Hemianthus micranthemoides (ok this plant is annoying me since I would like a bush but I gave 10 stems I received off someone to my brother but his new snail ate it all then I realized I wanted this plant and my 1 tiny stem is bearly making a comeback ...)
hygrophilia corymbosa 'angustifolia' i believe it's this one the leaves are almost 10+' long and the stalk is kinda more woody than limpy
hygrophilia polysperma 'rosanervig'
ludwigia repens (i would like to get the 'rubin version'
Micrathemum umbrosum
Nesaea crassicaulis (currently have one stem)
Rotala rotundifolia
rotala macrandra

these are the plants in my main tank, I plan to pull out a few species out soon, mainly rotala roundfolia and bacopa and the sunset hygro

plants I'm trying to get off some local people are:
Barclaya longifolia ‘red’
Lobelia cardinalis 'small form'
ludwigia arcuata
Limnophila aromatica

and plants in my low tech trying to be natural tank
Cryptocoryne wendtii
cryptocoryne x willisii 'lucens'
echindorus tenellus
Eusteralis stellata Sp
hygrophilia difformis

Quote:
Originally Posted by Stu
At the start of the day (i.e, what has built up over night), levels are at approx 33ppm and this dips to about 30ppm at the end of the day due to utilisation by the plants. (These levels are auto-calculated for me by Aquarix software. By using Chuck's calculator I get higher readings, but since you can only enter values of pH and KH to 0.1 and not 0.01 accuracy, I go with Aquarix - might be wrong!)

To be honest, it's not easy to say what is an "acceptable" level as different experiences have occured with different people. Some run around 40ppm, some have seen no problems with 50ppm, I read a source somewhere that fish will tollerate up to 100's of ppm of CO2! However, I would say that you have to take into account the species of fish exposed to the levels. Also, fish stock level, planting density, plant species, etc, etc..... again, hard to say definitively!

If you want to try more CO2, the key is to trial it carefully, upping by small amounts, then monitoring fish (and plant) health before going for the next upping. Be aware of the nighttime increase though..... if you run close to the limit for fish during the day, you might not realise the toxicity of the level from the increase at night until it's too late.

HTH



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post #6 of 7 (permalink) Old 03-06-2005, 11:31 AM
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Raymond, hardness kit is relatively inexpensive compared to pH meter or TDS meter. I am a lazy man, if TDS alone can give me all the answers, I would have used it already.

It's not possible to directly convert pH to CO2. The CO2 chart assumes CO2 is the only factor affecting pH. However, applicability of the CO2 chart would, I presume, questionable if you are using other chemical method to manipulate either pH or KH.

TDS in microseimen won't tell you how much KH your water has. It has been explained to you previously that it measures ALL dissolved mineral and mineral salt in the water, but it cannot distinguish which is which.

TDS is used mostly in hydroponics to measure fert level in water. But it is only a guide line, as it won't tell you if their water has more K or N or P.
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post #7 of 7 (permalink) Old 03-06-2005, 08:43 PM Thread Starter
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Oh, thx for the reply, I'm pretty lazy also so hope I could just take the 2 readings off the 2 meters and get an estimated amount of CO2, I guess in this case it won't work, I'll head down to the LFS to pick up a kit then so I can get an approximation to my co2 levels in my tank

Raymond

Quote:
Originally Posted by danmhippo
Raymond, hardness kit is relatively inexpensive compared to pH meter or TDS meter. I am a lazy man, if TDS alone can give me all the answers, I would have used it already.

It's not possible to directly convert pH to CO2. The CO2 chart assumes CO2 is the only factor affecting pH. However, applicability of the CO2 chart would, I presume, questionable if you are using other chemical method to manipulate either pH or KH.

TDS in microseimen won't tell you how much KH your water has. It has been explained to you previously that it measures ALL dissolved mineral and mineral salt in the water, but it cannot distinguish which is which.

TDS is used mostly in hydroponics to measure fert level in water. But it is only a guide line, as it won't tell you if their water has more K or N or P.


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