Hi Tom and others,

It is funny that I came across this thread for the first time today. Last week I was looking at my two 10g rotala tanks and I noticed a huge increase in pearling after doing my normal 90% water changes on the (left) rotala tank. Although this left tank pearls during the day, after a water change the tanks pearls like crazy. The right tank will also increase in pearling, but not as much because it already pearls like crazy. [by the way Tom, the one I was having trouble with (the left one) I ripped down, vacumed the gravel, cleaned the filter, replanted and now it is doing way better, still not up to its potential, but way better]

So to continue on.......I don't think this is actually due to CO2 in the water from the pipes because the water from the pipes is about 40ppm KH and a pH of almost 7 wich leaves the CO2 in the single digits (I will varify the CO2 content of the tap water as soon as I order some certified 4degreeKH water from Bill? for my drop checker.). I was planning on doing a negative control experiment next water change where I do the change about 3 hrs before the lights come on........If pearling occurs with the lights off then you know it is offgassing of other gasses dissolved in the water...........If I don't see the pearling within 15-30mins (about the normal time it takes to see the pearling with lights on) then I can assume that the pearling is due to one of two things: 1) exposure to CO2 from the water (unlikely see above) or the air (very likely as explained by Tom ealier in this thread).

The other interesting thing I have noticed is the left tank which actually has more CO2 dissolved in it than the right tank doesn't grow as well and doesn't pearl as much as the right tank, which has less CO2 (I determined the CO2 content by testing pH of the water in each aquarium and comparing the colors side by side; and by using the drop checkers in the aquariums with homemade 4degree KH solution). How could this be you ask? Well although the tanks are identical in every detail including the CO2 diffusor used, the left tank's CO2 diffuser doesn't work as well as the right tank's diffuser. The diffusor on the left realeases way bigger bubbles that go straight to the surface whereas the right diffusor releases tiny tiny bubbles of CO2 that go everywhere in the tank.

When I first setup both tanks I was wondering why the left tank was doing so bad........each tank had the same number of CO2 BPS. When I compared the tanks pH's side by side the left tank was always bluer. To compensate for the lower CO2 I started raising the BPS on the left tank which still didn't make the plants pearl like the right tank. Now I am at the stage where the left tank actually has more CO2 and it still isn't doing as well. This has to be due to the fine mist of CO2 that the right diffusor produces.

After I do the water change experiment this week I plan on switching the CO2 diffusors to see if this make a difference. If the left tank all of a sudden starts going crazy then it is obviously the CO2 mist not just how much dissolved CO2 is present in the water.

Anyway thats my experience thus far.

On another note I am having a problem with the drop checker returning to blue the next moring......I already read posts in other threads so I am going to buy the calibrated solution and move the drop checker in a higher flow area to see if that helps. I am using the ADA idicator solution that came with the drop checker. If the drop checker is still green the next moring I am going to raise the filter outflow to create more surface agitation. The flow rate is rediculous for this tank as it is (no glass on top, a fluval 104, 10g tank, and the outflow flows straight across the front of the tank)


Ken T.