F8 possibility - ph/substrate question.

[Bengoshi2000]

My 29 g tank has now fully cycled and my previous plan to put 4-5 DP's in it are running into a small snag... I can't find any DP's (short of resorting to mail-order). But one of my LFSs has had better luck sourcing F8's. I set up this tank with pfs for a substrate, but I've run across several articles here that indicate aragonite (sp?) sand is preferred due to the ph requirements of F8's. I've been checking the ph in my tank and it seems to be steady around 7. IIRC, F8's are better off closer to 8.

The Question: If I end up going with a pair of F8's is there anything I can do to raise/stabilize the ph (short of doing a full substrate swap)?

[jtbadco]

I would say stay with the pfs ....if you want to help to buffer the pH....you can add a couple of lbs of aragonite to the pfs.

I have a F8 puffer and they are an excellent choice for a smaller puffer. They only require light brackish (1.003-1.005) and some can be kept with (non-puffer) tank-mates.

[Bengoshi2000]

Thanks for the reply!

I did some further reading /searching here on the forum last nite and found that one option would be to put some crushed coral in a mesh bag and place that in my filter. I have an AC50. I won't be running it with the carbon, so I could put a bag of crushed coral there. Does this sound like a reasonable solution?

[RTR]

Crushed coral is not nearly as effective as aragonite in maintaining high GH, which to me is the most significant single factor in F-8 lifespan. Personally I would not keep F-8s over anything else. This is an indefinite-lifespan tank - say 15-20 years. To me, there is little point in not doing it right from the get-go. !.003 is fine long-term IF there is an aragonite substrate to maximize the GH.

If you wish to use an external filter with aragonite in it, that can work. I have done so myself, but I would not again, as it is many times the work (upkeep) of just using an aragonite substrate. Every few years you do have to add a little bit of aragonite to keep the volume up to original levels, but you do not need a heavy layer anyway.

HTH

[Bengoshi2000]

Thanks for weighing in RTR, I was hoping you would.

So for my 29, would it be best just to do a full substrate swap out? Or would a partial be ok? How much aragonite would I need for my 29 to reach optimal ph?

Related Query: Do GSP's require the same ph (and hence need aragonite)?

[jmiller]

I hope you get an answer because I've asked the same thing in a different thread and never got a response. I've been looking everywhere and still haven't found a definite answer. My situation is a little different in that my water is 8.0 straight out of the tap and no one can tell he how much the sand will raise it.

[Pufferpunk]

A 1-2" layer is good. Bite the bullet & swap it out.

[Flutter]

I recently had a similar question as well. My tap water is about 8.6 out of the tap and the water is very hard. I decided to go with aragonite because:
1. Only going to do this once and wanted to do it right from the start.
2. Your tap water changes throughout the year and years. Might as well not have to worry about it.
3. It can't hurt and AFAIK there are only benefits to the F8 health.
4. It was cheap, we went to a reefer and he sold us some environmentally gorgeous white sand for $11Cdn.
5. I don't plan on living here forever.

[RTR]

You cannot accurately predict the effects of aragonite on any given water. You are not looking for a specific pH - that is near-myth reinforced by folks who want to sell you artificial buffers. What you are going for is stability. You do not want the GH and especially the KH to vary any more than it must. If you start with pH 8.0 or 8.6 source water you will have better stability than if you start with pH 7.0 or lower water. Aragonite does not buffer infallibly to a certain pH. It dissolves faster in lower pH water than in higher, and in water at 8.6 its solution rate is tiny if detectable at all. What it is always doing is supporting the high KH which the F-8s seem to need by providing the right ions to the water when and as needed. The rate of loss from the solid to the dissolved form will vary with the total bioload of the system -it is affected by such things as overfeeding and clean-up of uneaten food and waste prior to its complete decomposition. Those are all things which increase the bioload on the system, and processing ammonia and other protein or nitrogen-containing materials to the simpler inorganic forms does eat KH. When the KH is used, the pH falls. When the pH falls, aragonite starts replenishing it. We select aragonite because it dissolves better. Aragonite is better than crushed coral - it does not require as much pH reduction before it starts working, so it is better at maintaining the needed high pH/alkalinity. Crushed coral is better than dolomite (which is not very effective (nor often offered anymore), but not nearly as good as aragonite.

The quantity you need is not great. A 1" layer is plenty for me in a minumum 15 gallon tank for one F-8. But that tank is set with OE-RFUG, vacuumed weekly at the outside (may be more frequent), and has 50% partials weekly, and alternate-day only feeding without overfeeding at all. If you have a passive substrate (without flow-through), you may go a bit deeper, but certainly not over 2" would ever be needed.

If you allow less water and substrate per F-8, or overfeed, or are not very conscientious (read as: neurotic) about vacuuming, you might need a bit more, or need to top up the substrate more often - these tanks lose substrate at about the level of FOWLR tanks, even though they appear to have lower bioloads. I suspect that this is due to low specific gravity used with these particular fish. The specific gravity used is so low that there in not nearly the GH & KH levels of full marine tanks, so we see solution of the substrate more in relation to the higher density tanks.

HTH

[jmiller]

Thank you very much for the writeup. Finally I understand why.

[RTR]

Glad to help - that is why we are here.