Misc Questions

[JasonB]

Hi everyone,

I have a couple questions I'd like to get your input on.

1. I have a 77 Gallon planted tank with 300 Watts of lighting. 40 of those Watts is with a 2800K plant light. My other 260 Watts is 6700K. I'm wondering if it would be better to change out that 2800K with another 6700K?

2. My Temperature has been on the rise, some of which I contribute to the lighting, some to the weather. Any suggestions on bringing that temp down? My water's at 88 degrees!

3. When I first started CO2 injection, my KH was 110mg/l and pH was 7.9. Now my pH is 7.0 but my kH has risen to 200mg/l Any ideas why this might have happened? I haven't added any chemicals other than plant nutrients and a UV sterilizer (I had some Green Water Algae and this cleared it up). The kH started to go up around the time of the bloom and hasn't dropped since even though the bloom has cleared up. When I do my 50% Water change it seems to drop the kH by 10mg/l - this has happened twice now. I perform the water change each week and using E.I. method. The tank is 6 weeks old. The increase happened about 3 days after I got my pH down to 7.0 from 7.8 using pressurized CO2 injection.

Thanks for any help you can offer!

J.

 

[craynerd]

1) I would personally find a 2800K too red and so would change it for a 6500K (i am currently using 6000K tubes)

2) I have never used one myself, since the weather over here in the UK has never got hot enough but, lots of people use cooling fans to bring the temp down. I would google it, or check out APC.

3) No, confusing. Your first values give you a CO2 conc. of only 2ppm ?
Sorry can`t help you.


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Hope answers 1 and 2 are of use.

Chris

 

[JasonB]

Thanks and Sorry about #3 - there's a lot of info in there. I guess what I should have said was just prior to adding my CO2, my kh was 110 and my ph was 7.9. Shortly after, my ph went down to 7.0 and my kh started to rise to the numbers indicated.

Thanks again!

J.

 

[craynerd]

KH and pH are related and therefore change proportionately.

At first with a pH 7.9 and Kh 110 your CO2 concentration was about 4ppm, which sounds about right with no CO2 injection

After adding CO2, you are adding more carbonate ions which makes the water more acidic, hence the pH drop to 7. this directly effects the KH which is why it shifted to 200, giving you a CO2 conc. of about 35ppm which sounds great.

so basically it is all seems correct. When you add the CO2 it will drive your pH down and increase your KH. When you water change you "reset" the water, remove some of the carbonic acid and so your pH increase and your KH drops again. This will soon be reversed again as you add more CO2 and the pH will drop and the KH will begin to rise.

All sounds perfectly fine to me and a CO2 conc. of 35ppm sounds great!

IMO you mention about the algae, i don`t think it has any part to play in this issue.

Hope that helps mate. It makes a little more sense, i just hope i have understood you correctly.

Chris

 

[JasonB]

Thanks, this helps a lot. I guess I got a little concerned because I had expected my pH to drop with the addition of CO2 but I didn't know my kH would increase because of it.

Thanks again!

J.