Need help with hardness and pH

[TheSugarBear]

I have a 55gal long tank.

Tank parameters currently:
Temp: 77
pH: 7.2
KH: 2.5
NO2+: 0
NO3+: 12.5 mg/L
NH4: 0

I am gunning for a planted tank with tetras, angels, corys, plecos, and eventually a pair of German Blue Rams. Right now I have 20 tetras, 4 medium angels, 2 corys, 2 ottos, 2 plecos, 4 swordtails (soon to be traded), and one stray platy (most of these came with the tank which was fully cycled and bought used). I have 2 Amazon Swords, 1 Rubin Sword, and some baby swords and java ferns. All living things seem to be doing fine.

I've had my DIY CO2 system running for 3 days now. It is putting out 6-8 bubbles per minute on the bubble ladder. They weren't being completely absorbed into the water so I rigged a powerhead to "catch" the bubbles that escape the ladder. It chews them up and spits them out and they seem to be getting 90% absorbed this way. Oddly the addition of the CO2 has effected my pH levels in no way at all which makes me wonder if something is wrong...

My question:

Given the above how can I safely lower my pH to 6.2-6.5 and raise my KH to 6? The reason I wish to do so is most material I have read suggest those levels for my desired plants and fish.

 

[neilanh]

First, I'm concerned with your NO3 level. 20ppm of nitrIte is toxic to fish, and if that's an accurate reading, I suspect your fish will, if they haven't already, deteriorate very quickly.

Assuming that you mean 0 NO3 and 20 NH4, that's no problem.

You want to lower your pH, but based on what? Injecting CO2 at higher levels will lower your pH while increasing your CO2 level. If that's you're goal, you'll want to do that by increasing your injection in your DIY system, or purchasing a pressurized system.

As for your kH, soft water like that is good for the rams you want. However, if you did need to increase your kH, you can add crushed coral in your tank or your filter to do that.

 

[TheSugarBear]

Shucks... I didn't write it down. I'll test again and post in about 20 minutes :?

Edit:

Data corrected. NO3 was errant.

 

[jsoong]

First, I'm concerned with your NO3 level. 20ppm of nitrIte is toxic to fish, and if that's an accurate reading, I suspect your fish will, if they haven't already, deteriorate very quickly.

Assuming that you mean 0 NO3 and 20 NH4, that's no problem.

NO3 is not nitrIte, it is nitrAte ...... NO2 is nitrite & that is zero. NO3 at 10 is OK for a planted tank.

NH4 is ammonia, NOT good at all!! Maybe you ar thinking nitrates?


OK, back to the original post ... The KH is a bit low to safely add CO2, you risk sudden & drastic pH drop. You can add a bit of crush coral to bring that up to 4 or so, that will maintain better pH stability.

Now, if the pH did not change with your CO2 setup, it is likely you don't have enough dissolving into the water. May be you can try adding some kind of a reactor vessel to trap the CO2 so it will dissolve completely. Also, how much surface water movement you have? Too much & the CO2 gets outgassed & won't raise the level in the water.

 

[jsoong]

One more thing .... If your KH is 6, you would aim for pH of 6.8-7.0 with CO2 injection (not 6.2 as in the question). This gives CO2 of about 20-30 ppm, just what you want.

At your current KH, you would need to see pH drop to 6.0-6.2 to get to the same CO2 level, which is getting too low. <Hence the recommendation to increase the KH.>

 

[TheSugarBear]

Excellent reply. Thank you.

Any idea how much crushed coral I should purchase considering that this is a 55gal tank?

 

[neilanh]

Thanks JSoong... You're exactly right. I'm so used to people showing their readings in order from ammonia, nitrite, then nitrate, that I jumped the gun and even managed to follow suit. I apologize for any confusion.

 

[rich311k]

My KH is 1 and I inject CO2 I have had no crazy drops or massive fish deaths. Once you get it set right you will have nothing to worry about. The PH from CO2 does not effect the fish. As long as the CO2 is at reasonable levels and your KH stays steady you will be fine. A lot of pretty plants like a low KH.

 

[Purrbox]

Could you describe your CO2 system in greater detail? I've got a feeling that you probably aren't producing enough CO2 for the size aquarium combined with an inefficient diffusion method (the Ladder). Also are you using an airstone, biowheel, or anything else that would be causing a lot of turbulence and gassing off what little CO2 your injecting?

Really with that size tank it's extremely difficult to get good consistant CO2 levels, and you'd be much better off with pressurized if you can afford it. It really does make a world of difference.

Don't worry about crashing your PH, there's a lot of people that are injecting CO2 with extremely soft water and they're not running into any problems. No need to mess with the KH just for CO2 injection. The biggest problem is getting an accurate CO2 reading when you have a low KH, this is where using either a pen pH meter and/or a CO2 drop checker can come in very handy.

 

[Plantbrain]

KH is define, just use that, especially for the fish kept.
Add enough CO2 to drive the pH to 6.4 and keep it right around there.
Do not use anything other than CO2 to do this.

Do not play with KH and assume that adding more KH will allow you to add less CO2, it does not work that way.

If you need more CO2, then add more CO2, it's a rather simple concept, but folks get all tied up monkeying with pH and KH changes. We are just trying to measure the CO2 with pH/KH.

That's all.

If you desire more CO2, then well, obviously, add more CO2 gas!
There's no issue of pH crash or anything else.

As long as the CO2 supply is stable and you can get a reading and maintain that rate, the KH is immaterial as far as most plants are concerned.

You have nice low KH, so use that.
This is less work for you and cheaper/easier/simpler all the way around.

Regards,
Tom Barr


Regards,
Tom Barr

 

[TheSugarBear]

First I want to say that I appreciate all of this advice so much. Thank you!

@Purrbox: CO2 system is a DIY system comprised of a clear 3liter thick plastic juice bottle with a threaded bulkhead through the cap. The gas then runs through CO2 proof tubing to a cheap hard plastic Tetra brand check valve and on up to the Hagen bubble ladder. The bubbles never come close to being fully absorbed in their climb up the ladder (I'd say they only get 50% absorbed) so I rigged the air intake line from a small 120gph powerhead so that it sucks up the unabsorbed bubble that would normal escape to the surface and chops it into many tiny bubbles that are disfused in the stream from the powerhead. Only a few tiny bubbles survive to hit the surface. The yeast brew is your own recipe from another thread utilizing champagne yeast but minus the protein drink mix. It probably fills only half of the bottle. While checking something entirely unrealated tonight I discovered that there was a decent kink in my tubing. After fixing that I am now getting 20-22 bubbles per minute about the size of a pea!

I do have a bit of surface rippling caused by the return from my canister filter (Rena X3) and I will adjust that and see if my pH drops due to retention of CO2.

I saw a mention of drop checkers and looked them up. To tell you the truth they looked a bit scary. What happens if the test solution escapes into your tank?

 

[Purrbox]

Okay, looks like your diffusion method is fine for now. It may need tweaking after you improve your CO2 production however. Basically you aren't producing anywhere near enough CO2 for that size tank. You need approximately 2 Liters of CO2 production for every 10 gallons of aquarium So with a 55 gallon aquarium you'd need about six 2 Liter bottles, four 3 Liter bottles, or three gallon bottles. The benefit of running at least two bottles is that you can rotate when you change the CO2 mix which will help keep CO2 levels more constant which helps to prevent BBA.

I'd increase your production first. If you're still having problems with CO2 levels then look at adjusting the filter output to reduce the ripple. A little bit of a ripple is good for O2 exchange, but it will gas off some of the CO2.

I'm using the Red Sea CO2 Indicator and have accidently turned it completely upside down for a couple moments without any of the solution escaping into the tank. If you're worried about it you can always buy/build one of the ones that uses a tyvek membrane for gas exchange. It has a faster reaction time and less chance of the solution accidently getting in the tank.