ph drop after large water change?

sCeRaXn said:
Ok so my kh test kit finally got here, which means ill probably be adding my c02 either today or some time this weekend. My ph is still holding steady at 6.8 and my kh is at 40ppm. What should my target kh number be?
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that's pretty low KH at 2.2 dKH(if i did my math right)

you should be at 3-4 dKH
should be around 70ppm

btw make your own 4 dKH solution ..use distilled or RO water ans add baking soda (a little at a time and I mean a little)
 
Star_Rider said:
that's pretty low KH at 2.2 dKH(if i did my math right)

you should be at 3-4 dKH
should be around 70ppm

btw make your own 4 dKH solution ..use distilled or RO water ans add baking soda (a little at a time and I mean a little)
Click to expand...

Well i think i figured out what my problem. I tested my tank for phosphate and it has alot more than it should. Then i tested my tap water and sure enough...phosphate(5-6ppm worth). Since phosphate basically replaces carbonate as the main "buffer", is it safe to assume that my KH and pH readings are gonna be inaccurate? If so, then what filter media should i use to remove the phosphate?

BTW-I just got off the phone with the city and appearantly they treat the pottable holding tanks with phosphate 4 times a year to help replace certain chemicals that are stripped through the filtering stage. So hopefully this is just temporary.
 
I don't believe phosphate affect the KH reading as it is a measure of carbonates.
I am also not sure phosphate will buffer pH. which could explain the drop in pH since you have low carbonates.
 
Well i did a little research and found out that KH test kits technically measure the buffering ability of the water. In a community tank, carbonates are what do the buffering...therefore kh=carbonate hardness(a "pure" reading). However, phosphate is also a buffering agent so when its added to a tank itll throw off the KH reading from your standard test kit. The only way to test the true KH reading of a tank that has phosphates is if you had a kit that only tested for carbonates, then did alot of math lol
 
So first i have to figure out how to get rid of the phosphate in my tank. Then ill be able to get a true KH reading so ill know where i really stand. What kind of filter media can be used to remove phosphates? Are there any "natural" ways of doing this(like adding cc to raise ph)?

btw-Heres one of my sources for the above info. I used two other sites but i cant seem to find them now. Ill post them up when i find them.

http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm
 
Well i just jumped the gun a little. I just set up my pressurized c02 system knowing that i wont be able to properly test things for a few days. I did some research and found out that everyone using c02 on a 55 ends up with atleast 1.5-2bps, and most of them with setups like mine are well over 2bps. So to be safe i set mine up just shy of 1bps(50bpm) and hopefully itll be alright until i get my drop checker and proper test kit. Then ill be able to fine tune it, but as of right now i think ill be fine. I know my KH is low but im hoping that has more to do with the phosphates altering my test results.
 
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