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low pH

Joined
May 20, 2013
Messages
10
Hi all!
It's been a while since I've posted here. I have terrible lurker tendencies. I am well on my way on the octopus odyssey. I have all my equipment and have been running the system for about 3 months. I have a brittle star and a sergeant major fish (which was almost free). I am having an issue with pH. It's been great (8.2) up until about a month ago. It is slowly going down, and I don't know what else to do. It's down to 7.6 now. I've done 2 25% water changes, and a through cleaning of the substrate. I'm considering adding a buffer, as a last resort. Does anyone have any advise?
Thanks!
 
Hi Olad, welcome back!

Adding some aragonite sand might help raise the pH.

Also, various salt mixtures have different pH values after mixing. I found Topic Marin to be quite good at maintaining a pH of 8.2. People keeping a fish only tank sometimes prefer lower pH values.

Another alterative is to mix some buffer into your new water for water changes.

Nancy
 
PH is a bit odd and fluctuates with CO2 concentration and temperature. We smoke so some of our problem may have been the extra CO2 in the room but I don't have a lot of faith in that reason. RO/DI water is PH neutral and your salt mix and existing tank water will be the major impacts. If you are using tap (NOT recommended unless you are using an RO/DI filter) or purchased water, test it before putting it into the tank to see if it is 7 or higher. My tap water is quite acid (6.2) but the RO/DI process should result in a PH of about 7 (otherwise you - or your water supplier - may need a new RO filter). If your new water is 7 it will take on the PH of the tank (now low so it won't raise it, no matter how much you exchange). For years we had to add buffer but eventually, our tanks stabilized (possibly with absorption of the buffer into the argonite substrate but that is second guessing). GO SLOWLY (adding to your NEW water ONLY) with adding buffer as most starfish are VERY sensitive to PH changes and tend to dissolve if the change is not gradual. I also recommend using a buffer that is designed for marine tanks and not something like baking soda that will work but can raise the PH too quickly and too high.
 
Thanks for the quick responses!
I think I'll try adding the buffer to the new water during water changes. Just a few questions: Normally I do a 25% water change every 3 weeks or so. Should I do it more often? Should I bring the pH up to 8.2 each time, or raise it incrementally for each change? How long do you reckon it will take to bring the tank pH up? I'm on month 4 of keeping a tank. I'm hoping to get an octopus in a month or two. Think it'll be ready by then?
Thanks!
 
You want to target 8.4 on the PH and a specific gravity (salinity) of .026 (full ocean, not the lower typical fish only tank numbers). I would recommend doing a smaller water change weekly and adding fully buffered water to the sump (if you have one) rather than directly to the tank. I also think you need to add a heavier bio load to the tank to bring up the bacteria before adding your main, very messy resident (think very large fish in terms of waste production). You can do this by over feeding and using meaty foods (like chopped up table shrimp - your brittle star will love it and it decomposes to ammonia quickly). Be sure to clean out anything that is not eaten and disturb your substrate during your water change as overfeeding will also increase your nitrates. I noticed you said serpent star and not starfish so you have much less concern with the PH jump (but still don't want an immediate change). You can add another serpent star (avoid the green variety but there are several interesting options. I am extremely fond of the red ones as they add color, often live with the octopus and are sometimes out during the day. The harlequins are distinctive looking but hide most of the daylight hours except during feeding) and hermit crabs (I like the red legs over most others and they seem to survive octos well). Snails can be added as well. They may or may not become octo food but will either scavenge or help with algae. Adding a pencil urchin has some benefits for both cleaning your rocks and scavenging but they often start nibbling on soft coral if you have any in the tank. Mushrooms are often a nice choice for adding color and will eat tiny meaty foods as well. You can also add a few clams (again, these may become octo food depending upon animal. You can serve them on the half shell as an occasional change of diet but they do well in most reef tanks and can be used as a minor clean-up animal until they are eaten.

Fish, however, are a big no. Damsels of any kind are likely to pick on an octopus and I will encourage you to remove the Sergeant Major before adding your octopus (your LSF may accept it and may give you something in trade - don't expect much though). Often the octopus will take matters into its own arms with fish but you risk the chance of the octopus being nipped, leaving it open to infection. Sadly, damsels are often one of the hardest to remove from a tank without disrupting the rock work.
 
Thanks for the advice on the water changes. I'll start that right away.
As for increasing the bio load, I was planning on adding a few critters, but thought it best to wait until I got the pH back up. I've been doing research and I was considering mushrooms, pencil urchins, and/or peppermint shrimp. It's good to know that I'm not far off track in my expectations. I'm not especially happy with my brittle star since he NEVER comes out. I thought he was dead for a while, but I happened to catch his arms wiggling out from his hiding place in the rocks at night once. I know Sarge wasn't the best choice, but he was kinda "thrown in" with the live rock deal when I bought it. I'm pretty sure he'll take it back since I observed someone else returning fish while I was there.
 
I've kept peps from time to time and recommend only keeping two as they tend to gang up on other animals (may not happen successfully with an octopus but they will kill small fish). Usually I see one get eaten and the other surviving. They will definitely investigate an octopus but at least one will learn to stay (mostly) on the other side of the tank. Do put them in the tank well ahead of the octopus as once the octo knows you are delivering food, almost anything you put into the tank while it is watching is considered fair game (may not be eaten but will be investigated as food). Needless to say, do not put expensive shrimp in the tank with an octopus.

If you happen to see one of these at your LSF, I highly recommend them. We keep one in each of the octo tanks and they all have the name Pesky. Strangely, they hide like other serpents when there is no octo in residence but often live in the octo's den (which helps locate a recluse animal sometimes) and often come out in the daylight when they have an octo companion (we are never sure if they pester the octo but seem to be accepted as a resident). They are great scavengers and can be easily hand fed pieces of shrimp (either literally by hand or with a pipette). Sometimes they get down right grabby (but are totally harmless). If you feed at the same time each night and locate your current serpent, you can train it to at least show its arms at feeding time :biggrin2:. They all seem to love small pieces of table shrimp.

Another star I like to keep goes by the common name Thorny Starfish. In spite of what you may read, I have found them to be meat eaters (possibly also eating algae) and hardy (unlike many other stars). They are one of the few that are day active and can be very bright orange (colors range from dull brownish orange to very bright). You definitely need to get your PH stable and higher before adding one though.
 
Ok. I'm in big trouble now. I did the small water changes with the pH buffer. It went up to 8.4 very quickly, but within a few days it would drop right down to 7.8 again. Then my Sarge died this weekend. Two days after that I had a major ammonia spike. It was as high as 1.0 ppm. I took out my brittle star but I'm not confident he's gonna make it. So now I have a 55 gallon tank with nothing but live rock in it. Do I just do like an 80% water change? How disruptive will that be?
I think I'm gonna take a water sample to my LFS and ask them to test it to be sure my results are correct. They will probably recommend I add some expensive chemicals because that's what they do. Any other advice?
What can cause such a spike in ammonia?? How do I prevent this from happening again?
 
Ammonia is caused by something dead in the tank. Usually we initially see this with stuff dieing on the live rock. You should not be seeing it after 3 months if the tank cycled but if you changed too much water during the initial cycle, it may have delayed the spike you should have originally seen and not completed the ammonia to nitrite to nitrate conversion and creating enough bacteria to quickly convert the next round of ammonia.

One thing I have found that will spike a tank (besides dead animals you know about) is sponge inside LR. Most sponge won't survive being taken out of the ocean (though tiny fragments may show up healthy after a couple of years) and is usually cleaned off rock intended for tanks but it can be hidden inside or holding pieces together that make it appear as one piece.

I think I would continue to monitor your tank without changing water for a couple of weeks and see if you see the ammonia drop and nitrite elevate. If you don't see the conversion and ammonia continues to rise, I would almost bet on sponge. It is also possible you had a mantis or other critter hidden in your LR that has expired. I would NOT use any chemicals to try to mitigate the problem, finding the source is a better answer.

Are you running a sump? If so, is it open to the air or closed? Do you have a skimmer? I am wondering about gas exchange and eliminating your CO2 (but you really did not have much in there that would use much oxygen). You can try a simple air pump with a wand bubbler to see if this helps but would be best in a sump to prevent air getting under the mantle when the tank is octo populated. If it does help stabilize your PH, then move it close to the surface if you don't have a sump. The other thing that impacts PH is temperature. Since we are in a colder season, did the room temperature changed about the time you noticed a PH drop?
 
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