how do i maintain PH while dropping SG?

[my name is mike]

hi, i am in the process of dropping my SG slowly so i can plant my brackish tank.

i just realized that this may drop my PH since i am adding less instant ocean with every change (and instant ocean helps buffer ph - correct?)

my PH is currently at 8.0 and i do not have any crushed coral (substrate is black sand and gravel)

would adding some coral remove my worries ??? if so, how much and in what form ???

[Peregrine]

What is the PH of your source water?

[Pufferpunk]

What fish are you keeping in there?

[RTR]

What is your tap water KH? Adding bicarbab (before the water is added to the tank, please) will boost the KH and support the higher pH. This is why I use aragonite substrates in low brackish, it helps keep high pH stable. If you wish to keep the current substrate, an external canister with aragonite will serve the same purpose. Boost make-up water to the pH you want with sodium bacarbonate and the canister load will maintain it. Periodically you do need to rinse the aragonite well to remove biofilms and any collected debris as such can slow the solution of the material.

[my name is mike]

I am keeping a figure 8 and two mollies (the mollies are temporary but will be in there through the planting most likely) ---

i do not know the kh (dont have a reagent for that) -- but the ph of the tap is 7.4

[RTR]

Freshly drawn tap may not be at a stable pH (dissolved CO2 and tempory buffers added by the utility commonly give different reults than are seen with aged water), so does not tell us much.

You should not attempt any water modifications without the test equipment. That can lead to real problems. KH testing is inexpensive and easy.

[my name is mike]

ok ,,, ill get a kh test --

what should i look for ???

my guess is that if it is significantly hard, i should be ok --- is that correct?

[RTR]

Moderate to high KH will be more stable for you. High Kh is likely to be relatively unchanging and your pH should not shift easily in that case.

[my name is mike]

thanks so much for the help ---

ill post my kh reading when i get the test (prob tomorrow)

if it is not too hard, adding coral or aragonite to my substrate would be the way to go correct?

[RTR]

For me it is, but I have also used external canisters of coral or aragonite.

[my name is mike]

i was looking at aragonite substrates to maybe switch over in the near future (or if my kh comes out too soft) -- i found some that were black, not white (which seems to be more common) -- does the black stuff do the same job in your opinion?

[nmonks]

I'd tend to forget about using aragonitic substrates in a planted brackish water aquarium. Most plants don't like coral sand. They far prefer laterite enriched fine gravel, aquatic soil, etc. There are lots of options depending on the plants you're keeping. Regardless, you need to optimise the lighting and substrate to compensate for the salinity in the water, which will be stressing the plants to some degree.

I'd suggest putting some type of hardening substance in the filter rather than the substrate. In the filter you can clean and replace the stuff much more easily, and you can control the amount used to optimise the hardness and pH relative to what your fish and plants want.

TBH, I'd be surprised if the marine salt mix and the hardness in your local water supply aren't adequate by themselves. A figure-8 puffer doesn't need a huge amount of hardness, and pH 7.5 should be fine. It's different with, say, scats and monos, where you need a pH a bit higher for best results.

Cheers, Neale

[RTR]

All my efforts with orange chromides in very light BW were in planted tanks, with fairly coarse aragonite from large sand to fine gravel sized particles. It worked just fine for me. I do disagree that plants dislike calacreous substrates - not in my experience. I also disagree that laterite is at all required. Laterite, or mulm from an old tank, or a milled peat fine layer.r fully mineralized soil under the substrate all make start-up a bit simpler, but are not required.

[nmonks]

RTR --

I disagree. Plant growth is so much better in tanks with a loamy or somehow enriched substrate. Sure, certainly plants don't mind coral sand or gravel. Vallisneria spp. spring to mind there. But as soon as you start going for things like Crinum spp., Samolus valerandi, and Cryptocoryne ciliata, ideal (and naturally) brackish water plants by the way, then substrate becomes more important.

I'm not saying you have to go down the Amano route just to have some nice plants, but investing a little time getting the substrate right to begin with pays handsomely down the road.

Cheers, Neale

[my name is mike]

intersting discussion -- thanks for all the input, it's really helpful for a novice like myself -- id be lost without this forum and my fish would suffer, so thanks ---

finally got a harness reading -- On my test it said GH indicated hardness and KH alkalinity

GH - 150 ppm
KH - 150 ppm
PH - 7.4

to begin planting, do i need my SG at 1.000 or would 1.001 be sufficiently low ???