Comments pls on my water change amount

[Byron Amazonas]

Thanks for the info, as usual, Byron. It seems a little difficult to discern what the aeration is doing with the CO2 - whether it is increasing the amount of CO2 or decreasing it (fish respiring at the surface, surface agitation fixing that) to me, anyway and I'm sorry for not being clearer - I meant that I could aerate the new water in the bucket to be used for the water change the next day (a common suggestion) overnight if I want to, avoiding some of the CO2 peaks from undegassed tap water. Btw, I have adopted the practice of stirring the tap water until it becomes clear. I assume that this does something to de-CO2 the tap water.

I think that aerating the tank forces the water to dissolve more atmosphere (with a corresponding higher dissolved atmospheric pressure) including CO2. Or maybe I'm looking at this the wrong way, and it attempts to de-gas tank water and you get less dissolved atmospheric gases. Uh! Lucky if I get out of this with all my feathers intact. Sounds like it depends on what the dissolved atmospheric pressure is vs. the equilibrium dissolved atmospheric pressure. If there are more atmospheric gases dissolved, aeration would, it seems to me, try to release excess gases. Conversely, if there are less dissolved gases than the equilibrium point, aeration would help bring more atmosphere into solution. It seems to me that any water movement would release gases, including CO2, at night when more of the dissolved bacteria-generated CO2 is building up, and that the dissolved gas level is always trying to get back to equilibrium with the atmosphere.

And, to wrap things up, it seems to me that in the typical situation of fish gasping at the surface, the fish might be having trouble breathing because of too much CO2. I'm not sure. Probably not in a low-tech tank. Low water circulation not bringing enough O2 into the tank?

Steven

Not having measuring devices for Oxygen and CO2, I can't test for levels but only go from observation when this or that is changed. Water surface disturbance increases the exchange of gasses, primarily O and CO2. The levels of each in the water and the air determine which way they exchange, from denser to lighter. Normally, without any addition of CO2, the exchange brings in more oxygen (to the water) and drives out CO2. CO2 builds during the night in planted tanks, from respiration of fish, plants and bacteria but more importantly from the breakdown of organics which is the largest source of CO2. In your soil substrate, this is even greater, at least for the first few months. And as the plants are not taking in all this CO2 during darkness, this is when it impacts fish.

Plants require only a small dissolved oxygen level. Too much oxygen entering the water is actually detrimental to plants (not directly to fish) because some minerals readily bind with oxygen and become too large to be taken up by plants; iron is one, there are others. So a nutrient deficiency for plants can occur. During darkness, oxygen may decrease sufficiently to be detrimental to fish, as I believe in some of my tanks, which is why my increasing the surface movement just a bit has resulted in a noticeable change in fish response during the early morning.

With respect to the CO2 in the tap water, I would not fuss over that; it will get used up within a few hours, and I have never noticed any detrimental effect on the plants from this. Quite the opposite in fact.

Byron.

 

[Steven 1]

Hi Byron,

By now you should know that I like solving tortuous problems and figuring out things that are complex. Maybe I overthink. I wish in this case I knew more about Chemistry and Dalton's Law of Partial Pressures so I could figure this out. I suppose I have the means to learn it - maybe I will.

I read that with CO2, a consistent level is important. Maybe this was about an injected CO2 tank, idk. I could just let the water sit overnight in the bucket - requires a little forethought. [This was about the drawbacks of DIY yeast CO2]

Btw, in case you're interested, my plants have grown a lot in a short amount of time, so I raised the lights another 5-6", bringing the total amount raised to 10-12". These are 10W CFLs in aluminum dome "brooder" reflectors. I know I've said this before but my guess is that these reflectors are very efficient. Pictures forthcoming...

Talk to you next time,

Steven

 

[Byron Amazonas]

I read that with CO2, a consistent level is important. Maybe this was about an injected CO2 tank, idk. I could just let the water sit overnight in the bucket - requires a little forethought. [This was about the drawbacks of DIY yeast CO2]

This is two rather different issues. DIY CO2 is (or should be) providing a regular consistent level of CO2. Long-term, this is important. Without a continual balance of all 17 nutrients and light, plants cannot photosynthesize and algae would have an advantage. One can see this when the light intensity weakens as tubes age for example; photosynthesis slows and algae increases.

Increased CO2 from a water change is temporary, and while some maintain this is detrimental to plants, I have certainly not seen this. I'm frankly not sure how I would see it, but given that the plant growth in all my 6 tanks is good, and given the real benefits of the water change to the fish, I am not about to stop. With my number of tanks, some being 100 gallons, I have no way to let water sit out even if I wanted to, lol. This temporary increase of CO2 probably allows the plants to photosynthesize a bit stronger/longer. Plants photosynthesize at the highest level possible, which is determined by the light intensity and nutrient availability. Photosynthesis slows when one of these is insufficient.

Btw, in case you're interested, my plants have grown a lot in a short amount of time, so I raised the lights another 5-6", bringing the total amount raised to 10-12". These are 10W CFLs in aluminum dome "brooder" reflectors. I know I've said this before but my guess is that these reflectors are very efficient. Pictures forthcoming...

This is most likely due to the increased CO2 from the organics in the soil. In new setups, it takes a few months (Diana Walstad says about a year) for a plain sand or gravel substrate to build up the organics to this level, which is one reason why plant growth is slow at first and then picks up considerably. You should (and obviously do) see this immediately.

Byron.

 

[Steven 1]

I took a couple of pictures of the tank this morning. I usually photograph at night to get rid of the reflections around the room.

The plants have grown a lot.



I am already having some second thoughts about the lights being up so high. I would like to replace the two 10Ws with two 8Ws and bring the reflectors down at least halfway.

 

[Byron Amazonas]

I don't know how powerful the reflectors are, but I would have two 10w CFL right on the tank glass. It is true the plants are growing, but not thickly, and that is usually a sign of insufficient (or minimum) light. With stronger light they will be more compact. Over my 10g and 20g, I have two 10w CFL 6500K are they sit on the glass.

 

[Steven 1]

The height of the lights seems a little much. I am hoping the 8Ws will be a little more manageable than the 10s. I have no top on the tank.

My Journal is at http://www.aquariacentral.com/forums/showthread.php?277094-Journal-Of-My-10g

Maybe I'm overcompensating for when the lights were on the rim of the tank and I got continuous algae. I'll start shopping for the 8Ws

As the tank stands now, I will keep an eye on the condition of the plants and hope the light isn't too weak. What prompted raising the bulbs was plant growth that was unusually fast for me and I started thinking that they must be taking up a lot of ferts growing like that. I'm really not used to it.

I want to take a straight-on pic tonight.