Using multiple drop checkers - The Planted Tank Forum
 
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post #1 of 13 (permalink) Old 01-18-2010, 06:26 PM Thread Starter
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Using multiple drop checkers

Does anyone use multiple drop checkers, each with a different dKH solution, to get a more accurate pH/CO2 reading? I just started using a drop checker today. When I attempted to make a 4 dKH solution, I realized I had messed up and made a 2.5 dKH solution. I figured that made the solution more sensitive to pH swings, but wasn't sure by how much.

Since I'm using DIY CO2 I figured more sensitive would be better anyway, since my CO2 levels were probably always well below 30ppm (that last part may be proving untrue in my tank). Then I found the following chart:

http://aquaticconcepts.thekrib.com/Co2/co2_faq.htm#T06

That got me thinking that using multiple drop checkers with different dKH solutions could be useful for getting a more accurate CO2 reading. Does anyone do this?

And for a somewhat unrelated question, I can't read my drop checker unless I take it out of the tank. When in the tank, once it changed towards green, it just started looking clear. Is this normal? I just did a water change yesterday, and the water is pretty clear right now.
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post #2 of 13 (permalink) Old 01-18-2010, 08:06 PM
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The ppm of CO2 at which the drop checker is green is proportional to the KH in degrees. So, a 2.5 dKH solution would be green at about 2.5/4 times 30, or about 20 ppm.

Multiple drop checkers are just overkill, and don't increase the accuracy at all. For one thing each one's reading would have the same inaccuracy due to difficulty in judging the color. Then, there is the fact that the ppm of CO2 varies at different spots in the tank, and it varies a lot. It is best to just rely on a single drop checker as a means of giving you the courage to jack up the bubble rate enough to get reasonably close to 30+ ppm. From there you have to slowly increase the bubble rate, a little each day, until you get some pearling within a couple of hours after the lights come on, or until the fish start to cluster near the top, or show other signs of discomfort with the CO2. That is the only really accurate way to get to the optimum CO2 concentration for any particular tank setup, short of buying a $2000 special CO2 concentration probe and meter.

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post #3 of 13 (permalink) Old 01-18-2010, 08:40 PM Thread Starter
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Quote:
Originally Posted by Hoppy View Post
The ppm of CO2 at which the drop checker is green is proportional to the KH in degrees. So, a 2.5 dKH solution would be green at about 2.5/4 times 30, or about 20 ppm.
Make sense, and the chart confirms this.

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Multiple drop checkers are just overkill, and don't increase the accuracy at all. For one thing each one's reading would have the same inaccuracy due to difficulty in judging the color.
This is the part I thought might improve with different dKH droppers in the tank. I have a very hard time reading the shades of green or blue. Maybe I'm just colorblind and can't tell if it is yellow/green or blue/green.

If I had two data points, I think that might help. For instance, for 30ppm the 2.5 dkH should show a pH 6.4 and the 4.0 dKh should show a pH of 6.6. I think with two reading like this I could narrow down which color(s) on the chart I'm looking at a little better.

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Then, there is the fact that the ppm of CO2 varies at different spots in the tank, and it varies a lot.
This also would seem to suggest more data points around the tank would give you a better picture of what your CO2 levels are. Maybe that 30ppm reading you are getting is from the part of the tank with the lowest CO2 levels.

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Originally Posted by Hoppy View Post
It is best to just rely on a single drop checker as a means of giving you the courage to jack up the bubble rate enough to get reasonably close to 30+ ppm. From there you have to slowly increase the bubble rate, a little each day, until you get some pearling within a couple of hours after the lights come on, or until the fish start to cluster near the top, or show other signs of discomfort with the CO2. That is the only really accurate way to get to the optimum CO2 concentration for any particular tank setup, short of buying a $2000 special CO2 concentration probe and meter.
I'm starting to get a sense that observation might play a bigger role in getting CO2 levels right than actual measurements.

The drop checker on my 46g is showing lime green, so I believe my pH is 6.4, maybe even a bit lower. This is with a 2.5 dKH solution, so I should be at around 30ppm, +/- more ppm than I care to acknowledge. I see some pearling on the bottom of some java ferns, but this may just be left over from last night's water change. Fish seem happy.

I'm using DIY CO2, with 4 two liter bottles, one new bottle rotated in each week.
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post #4 of 13 (permalink) Old 01-19-2010, 03:08 PM
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Tom Barr has been telling us for some time now that the plants are the best CO2 meter - watch them, not the drop checker. (He doesn't use drop checkers). My only problem with that is that those of us who lack the experience to communicate with the plants comfortably can't really tell what the plants are saying. At least the drop checker keeps you from misunderstanding the plants and ending up with 5 ppm of CO2, lots of BBA, and total confusion about what is wrong. The drop checker tells you when you are in the right ballpark with CO2, so from that point on you can watch the plants with a lot more confidence. I quit using my drop checker once I realized about what the optimum bubble rate for CO2 was for the tank I had then, but before that I was clueless.

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post #5 of 13 (permalink) Old 01-19-2010, 07:19 PM
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Quote:
Originally Posted by Hoppy View Post
My only problem with that is that those of us who lack the experience to communicate with the plants comfortably can't really tell what the plants are saying.
Totally off topic, but you made me think of a book: there's a series of sci-fi books by Kevin Anderson called The Saga of the Seven Suns in which people communicate to and through trees.

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post #6 of 13 (permalink) Old 01-20-2010, 01:44 AM Thread Starter
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This morning, even with the air stone on all night, the pH went down to about 6.2 with the 2.5 dKH solution. Kind of hard to tell for sure since yellow is 6.0 and the next color above is for 6.4, but it seemed to be between the two. This would put the CO2 at 46ppm.

I kept the air stone on all day, and also made up a 4 dKH solution. At the end of the day it was reading about 6.5, which would mean 36ppm. Looks like I'll need to keep the air stone on for a while until levels come down some.

I'm not getting much pearling. I have 2x39W T5HO with individual reflectors, raised about 3 inches. I recently added the original 25W T8 to get better coverage. I'm thinking maybe I should try lowering the T5HO.

I'm dosing EI, except no NO3 (40-50ppm already out of the tap). I added root tabs a couple of weeks ago hoping my amazon swords would perk up, but I'm no seeing much out of them yet.
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post #7 of 13 (permalink) Old 01-20-2010, 02:34 AM
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Have you verified that your NO3 really is that high? That means calibrating the NO3 test kit. If your test results are faulty you might be very low on nitrates, by not dosing any, and that would certainly reduce the pearling. Even if your tap water has 50 ppm of Nitrate, by the time you go a week without adding more, that level should drop well below 30 ppm. So, why not add about half of the EI suggest dosage, and see if that helps?

Also, if your fish are not showing distress from the CO2, you can increase the bubble rate until they begin to do so, then back off slightly to where they again don't. My experience was that my fish almost always ended up in a corner of the tank, looking like they wanted to leave, if I had too much CO2. I "calibrated" that response by accidentally going a bit too high and having a small number of fish die as a result. A few bottom dwelling fish would just lay on the bottom, sometimes on their side, when there was too much CO2.

With the light you have, if you have adequate fertilizing, and are providing good CO2, you should have lots of pearling, as well as good growth of the plants. Amazon swords should quickly outgrow even big tanks with those conditions, and without any root tabs.

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post #8 of 13 (permalink) Old 01-20-2010, 03:38 AM Thread Starter
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Have you verified that your NO3 really is that high? That means calibrating the NO3 test kit. If your test results are faulty you might be very low on nitrates, by not dosing any, and that would certainly reduce the pearling.
40ppm+ is common around here. Lab certified testing done on our well water from about 4 and 11 years ago showed ours in this range. My test kit (not calibrated) also shows about the same.

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Even if your tap water has 50 ppm of Nitrate, by the time you go a week without adding more, that level should drop well below 30 ppm. So, why not add about half of the EI suggest dosage, and see if that helps?
A few months ago I measured nitrates in the tank at around 15ppm after two weeks with no water changes. I've never bothered with a one week measurement (water changes are every 1 to 2 weeks, depending on how busy I am). I probably have a bit more CO2 now (was running 3 bottles at the time).

What is the target range for NO3? BTW, I dose K2SO4 to make up for not dosing KNO3 (in order to get enough K).

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Also, if your fish are not showing distress from the CO2, you can increase the bubble rate until they begin to do so, then back off slightly to where they again don't. My experience was that my fish almost always ended up in a corner of the tank, looking like they wanted to leave, if I had too much CO2. I "calibrated" that response by accidentally going a bit too high and having a small number of fish die as a result. A few bottom dwelling fish would just lay on the bottom, sometimes on their side, when there was too much CO2.
I saw one of my mollies (I have about 12) that was resting on a leaf near the surface. The rest were all very active. I think I saw this same one "breathing" at the surface earlier, although I wasn't so sure he wasn't just hoping to get some food.

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With the light you have, if you have adequate fertilizing, and are providing good CO2, you should have lots of pearling, as well as good growth of the plants. Amazon swords should quickly outgrow even big tanks with those conditions, and without any root tabs.
So your saying there is no need to lower the lighting fixture?

My amazon swords did grow out of the tank a year ago a couple of months after I setup the tank with Aquasoil. I think at the time I may have only had two bottles of CO2. Then the growth really slowed down after that. That was ok, until about 6 months ago when suddenly my BNP decided it liked chomping on them. Now they can't keep up with him.
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post #9 of 13 (permalink) Old 01-20-2010, 08:03 PM
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40 ppm of nitrates in the water is not too much, and you could double that before you might want to worry about it. Of course some species of fish or shrimp might be bothered by that much, but generally speaking, you are not near the limit. With that in mind, why not experiment by dosing at a reduced level per the EI tables, for a couple of weeks, just to see if it helps? If you are concerned, just do a 50% or so water change twice a week during that test. At least this would eliminate a shortage of nitrates as a possible problem.

Since you are using DIY CO2 it is unlikely that you will have too much CO2 for a 46 gallon tank, even with 4 bottles going. It may be that you are just short of CO2 for the amount of light you have.

I wouldn't lower the light fixture if it were me, unless it has really poor reflectors.

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post #10 of 13 (permalink) Old 01-20-2010, 09:16 PM Thread Starter
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I wasn't worried about going beyond 40ppm being a problem for the fish (although I constantly see people freak out for some reason when it "reaches" 10-15ppm). I was just wondering at what point is additional nitrate no longer a benefit to plants.

Today I cleaned the glass lid and lowered the light just as an experiment. Also I kept the 25w light on. No difference in pearling. I'll try dosing nitrates tomorrow since it is my macro feeding day. I have a Current USA Nova Extreme:

http://www.bigalsonline.com/BigAlsUS...000kfreshwater

I've always wondered about the pink freshwater bulb. It is so dim that it almost looks off next to the 10,000k. However, if I pull the 10,000k bulb, I can see that the pink freshwater bulb is actually on. Is this normal?

At what CO2 level do you get most of the growth you can expect from a plant. For example, will 15ppm give me 80% of the growth that 30ppm will give me? I'm curious because although there may be some doubt as to whether or not I'm really at 30ppm, I'm pretty sure it must be at least 15ppm, and I thought the main reason for pushing it to 30ppm was to reduce algae, not for even better plant growth.

If I have less than 15ppm, 2.5 dKH and 4 dKH drop checkers would need to be off by about .5 for it to be 15ppm or less. Also, my tank water pH has dropped from about 8.3 to 7.0, also supporting 30ppm or higher (both with the innacurate pH chart, and the pH/dkH chart for 10 dKH water, which is what my tank water is at).
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post #11 of 13 (permalink) Old 01-22-2010, 12:26 AM Thread Starter
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I added 1/2 tsp KNO3 today along with the other macros. Still no change. Only a few java ferns are showing pearling. They seem to be the younger, faster growing leaves.

I'm wondering if I'm not seeing much pearling because I don't have enough O2 saturation. I'd say the tank has about an average amount of foliage, but most if it is slow growth plants. The only fast growing plants are one Hygrophyla corymbosa and about a 3" x 12" area of dwarf sag, so I'm not so sure there is enough O2 being produce to saturate the water with O2 so pearling can happen.
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post #12 of 13 (permalink) Old 01-25-2010, 08:01 PM Thread Starter
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Yesterday I did my weekly DIY CO2 swap/replacement. Today I'm seeing some pearling streaming off the Hygrophyla corymbosa, one java fern leaf, and and something else in the back of the tank (can't quite make out the source). Previously all I saw were bubbles accumulating under some of the java fern leaves.

I didn't do a weekly water change yesterday. However, one other thing I did do was clean out the white fuzzy stuff accumulating in the CO2 Rex style reactor. It looked like a small ball of cotton on the tip of the rigid tubing, and at times over the past couple of months has made it difficult for the bubbles to get out until enough pressure built up. I'm not sure if that is helping also. Maybe less back pressure in the 2 liter bottles means less leaking.
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post #13 of 13 (permalink) Old 02-22-2010, 05:57 AM Thread Starter
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Thought I'd do an update. When I first started this thread, I was EI dosing a bit below what was recommended for a 40-60g (probably about 75%). I have a 46g, so probably 40g or less of water. I now dose a bit above, probably 125%. I've also added fert tabs, some just before starting this thread and a few more just after.

I'm seeing better results now. I definitely see more pearling. However, the biggest change I saw was in nitrate consumption. My nitrates are about 40-50ppm out of the tap. In the past if I didn't do a water change for two weeks, I'd see nitrates get down to about 15-20ppm, so I never worried about adding nitrates. However, now after just one week it was down to 10-15ppm. I might actually have to start dosing nitrates now, maybe 1/2 tsp late in the week.
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