Up, **** pH, up!

[Telek]

Ok, I've been trying to maintain a pH of around 8.2 in my tank for a while now (based on the datasheets I've read all of the fish I have like 8.1 to 8.4 range) but I just can't get it up. I tried 2 different "pH Up" products, the first one worked for about 8 hours, and now I have "Marine Buffer" stuff, but the pH keeps resetting every day to about 8.05.

I have a 2L plastic bottle (thoroughly washed) that I poked a small hole in the bottom so I can drip the solution slowly into the tank over the period of about 3 hours. I mix the recommended amount, and according to my digital meter the pH goes up to a nice 8.24, but within about 12 hours it's back down to 8.05.

I've got a 75 gallon tank with 95 lbs of rock (65lbs of fiji, 30 of spiderwick) and 80lbs of "live sand". Ammonia and Nitrites are negligable, Nitrates are fine too. Carbinate hardness is 250 (14dKh), General Hardness is about 350. Salinity is 1.023.

The fish don't seem to care, but I'd like it to be at least 8.2. Does it really matter? Is the hardness too high? If I keep dousing the tank will it eventually get higher? Is it bad to keep exposing the fish to pH changes like this every day? Is there a better way to raise the pH?

Thanks! (I did search but didn't find anything terribly useful)

 

[ccCapt]

The fish don't seem to care, but I'd like it to be at least 8.2. Does it really matter?

No. Your pH is fine at 8. Anywhere from 7.8 to 8.4 is good.

Is the hardness too high? If I keep dousing the tank will it eventually get higher?

Yes, and yes it will get higher if you keep dosing. Stop all dosing.

Is it bad to keep exposing the fish to pH changes like this every day?

No, changes in pH throughout the day is common.

Is there a better way to raise the pH?

Your pH is fine, but if want something to read....
Low pH: Causes and Cures
The "How To" Guide to Reef Aquarium Chemistry for Beginners, Part 3: pH

 

[Telek]

Thanks for the info. If 7.8 to 8.4 is fine, why do all references I can find recommend 8.1 to 8.4 then?

 

[jhampton_wsu]

I agree with ccCapt. I've always read that a stable ph which is lower than the ideal (though I don't think 8.05 is too low) is better than a constant swing up and down. I don't think 8.05-8.2 is an abnormal swing. My ph is 8.2 most of the day and drops to about 8.08 at night. Is the water at the top of your tank agitated by a power head? Agitated surface water will help raise your ph.

 

[roka64]

I agree, stability is better than "perfect", within reason. Do you have a cover on the tank?
Added surface ripple will increase your pH. I tried the buffering but it became a huge pain. I added a ph and pointed it to the top for more surface ripple and have not worried about it since.

 

[Telek]

Anyone?

 

[ccCapt]

What's the question?

 

[Ziggy953]

I thought your question was answered. Hmmm...what was the question?

 

[Tank2379]

Why do all references I can find recommend 8.1 to 8.4 then?

I think he is refereeing to this question guys....

 

[Ziggy953]

Ah...

Recommended is not always what happens in reality. My tank pretty much stays at 8.1 but it is 3 years old. Stability is the key. 7.8-8.4 is the target range but stability is what you are after.

 

[Telek]

Yeah sorry, got distracted and hit the reply button before my post was completed

Yes, I was referring to why things say 8.1-8.4 if 7.8-8.4 is fine.

Without any buffering for a few days now it's hovering around 7.9 at night and 8.05 during the day.

I have a powerhead and aerator. No skimmer or sump yet.

 

[Ziggy953]

Yeah sorry, got distracted and hit the reply button before my post was completed

Yes, I was referring to why things say 8.1-8.4 if 7.8-8.4 is fine.

Without any buffering for a few days now it's hovering around 7.9 at night and 8.05 during the day.

I have a powerhead and aerator. No skimmer or sump yet.

I think you are good to go. AS your tank matures the ph could eaisly rise to 8.1-8.3 and be stable there. You just don't want to see large changes from day to night.

 

[Tank2379]

Yeah right now mine is up and down but it stays at a stable level during the day 8.2 and for some reason it drops down to 7.7 @ night once the lights go out.... But I believe because I don't have any Moon Lights for night time so my system go into Pitch black dark mode....

 

[Telek]

I thought that I'd share a little bit of further research I did on this, it may be general knowledge to most people but I found it interesting. I'm writing this based on what I've learned, so I could be wrong on some parts.

The end result of biological activity produces nitric acid which seperates into hydrogen ions and nitrate. The hydrogen ions gradually combine with the bicarbonate ions to form carbonic acid which slowly breaks down into CO2 and water. Since the hydrogen ions are used in this process the pH doesn't go up much, ergo higher alkalinity creates "pH stability".

During the day (most) fish are more active which increases respiration which increases the H+ ions in the water which increases the pH. This is partially countered by an increase in dissolved CO2 from respiration, however that is more readily removed from the water by powerheads that cause surface agitation and aerators and photosynthetic processes in the tank that occur when there is light. This explains both why pH goes up during the day, and aerators and powerheads cause an "increase" in pH by decreasing the dissolved CO2.

Note that this stability actually consumes bicarbonate, so alkalinity will naturally decrease over time. Over longer periods of time, however, bicarbonate is "absorbed" into the parts of the aquarium including the rock and sand and corals and plants and filter media which acts to keep the alkalinity more stable. So the longer a tank has been in operation the more stable the bicarbonate levels will be, causing more stable pH levels.

 

[thincat]

If you still have ammonia and nitrite readings, no matter how small you are still in the cycling stage and its normal for your ph to react that way. How old is your tank? and what is a little ammonia and nitrite...readings please...

 

[Telek]

My previous tests showed Ammonia around 0.5ppm and Nitrites always "below zero" (the colour of the blue is paler than the lowest level on the scale). I know below zero isn't possible, but it's strange.

I stopped dosing after you guys recommended it (about a week ago) and the test that I did yesterday showed all 3 at zero. Alkalinity is also down a little to 13 dKH. The cold tap water that I treat and heat and use is 5dKH and has a TDS of 170ppm and comes out at 5.5C (42F) (as a side note hot tap water is 210ppm at 55C/132F).

I'm still thinking about getting an RO/DI system. My local water reports show very clean water, so it's hard to justify the large investment at this point, and the idea of schlepping buckets of water from the LFS every week is not very enticing. I've been doing 10 gallons out 15 gallons in every week (on a 75G tank). The aquarium is glass covered, but I installed a small fan in the back to reduce the temperature (what a difference that made!) so there's a fair amount of evaporation now.

I know that the aquarium water was already 12dKH before I started dosing, so I'm not sure where all the alkalinity is coming from.

 

[Kurt_Nelson]

I know that the aquarium water was already 12dKH before I started dosing, so I'm not sure where all the alkalinity is coming from.

It's coming from you dosing! (Or am I not reading that right?)

12 dkH is a totally acceptable number, versus the alkalinity levels you were mentioned in your first post. Many salts will mix up to around 12 dkH right out of the bucket. Dosing buffer will only elevate those numbers.

Regarding not being able to justify an RO/DI system, if you are keeping any amount of corals, it seems like an easy justification to make when you consider the financial investment in the corals. But hey... if the tap water isn't causing problems for you, I'm not one to say to change it. But if you do end up seeing algae issues, or poor polyp extension/expansion on your corals, it might be something to consider.

Also... 10 gallons out and 15 gallons in during water changes - you really want to shoot for consistant salinity between water changes, and you should be topping off at least every other day, if not daily. Also... don't forget that with evaporation, only the water evaporates - the salt stays behind. So if you're replacing that 5 gallons worth of evaporation with salt water, you're slowing elevating the salinity of your tank at every water change. And if you're replacing 5 gallons of evaporated water (that's over 5% of the tank volume) all at once, you're probably seeing really big salinity swings on water change day. Fish don't care for that much and if you see signs of stress/illness after water change day, that may be your culprit.

 

[Telek]

Thanks for the tips!

The water was 12dKH before any dosing, and the LFS guy recommended marine buffer to raise the pH because I was worried that lows of 7.8 were too low, and yes it caused a huge alkalinity rise (to a max of about 18dKH) so I stopped dosing about a week ago, and am down to 13dKH now.

Everything that I have read states that 8-10dKH is pretty much the max that you want for alkalinity, with some going as high as 12 if hard corals are kept (I don't have any corals at all right now).

Yes, I keep a close eye on salinity. 5g evap over a week out of 75g doesn't change the salinity that much (especially with all the ... salt creep that I seem to have), and I calculate and mix the replacement water accordingly to keep a proper salinity level. The tank stays in the 1.023 to 1.025 range, and replacement water is introduced with a air tube siphon and 5 gallons takes about 30 minutes to drain in, so even the replacement happens gradually to avoid massive swings.

I'll check the tap water after treatment and also after salt mix to see what the hardness is there.

Thanks!

 

[Telek]

Okie, so treated and heated tap water is identical to cold tap water (as expected) at 6dKH. After adding in the IO salt (to 1.023) and mixing and waiting it's about 12.75dKH (I say .75 because the 12th drop had a very slight yellowing, full change on drop 13). So that would explain why my alkalinity is so high.

 

[jhampton_wsu]

12 dkH is a totally acceptable number, versus the alkalinity levels you were mentioned in your first post. Many salts will mix up to around 12 dkH right out of the bucket. Dosing buffer will only elevate those numbers.

I'd listen to Kurt he seems to know what he's talking about.

Regarding not being able to justify an RO/DI system, if you are keeping any amount of corals, it seems like an easy justification to make when you consider the financial investment in the corals.

If you have enough corals that you need to suplement your sat mix by dosing you probably have a large enough investment. At the least spend the $ .35 or so on ro water from the grocery store. When I buy mine it tests 0 tds.

Also... 10 gallons out and 15 gallons in during water changes - you really want to shoot for consistant salinity between water changes, and you should be topping off at least every other day, if not daily. Also... don't forget that with evaporation, only the water evaporates - the salt stays behind.

The difference between a tank at 1.023 and 1.025 is noticeable to the corals and fish.

Jason