Partially concreted sand bed - reworking dosing

[don_chuwish]

So I've noticed a fair amount of my sand bed turning to rock. Especially around the base rock - it is as if my base rocks are growing. I pulled out some chunks and broke up some others that weren't too tough, but the stuff that is attached to the base rock is just too hard.
My dosing of ESV B-Ionic 2 part had been periodically increased until I observed that Ca and Alk stayed at stable levels, around:
Alk: 9.8dkh (Hanna)
Ca: 410-420ppm (Red Sea Pro)
pH: 7.85 - 7.95
By dosing both 65ml/night, from 8:00PM to 11:00AM, alternating 1 hour apart. So Ca at 8:00PM, Alk at 9:00PM, etc.

So last night I left the dosers turned off entirely. Today's measurements:
Alk: 8.74dkh
Ca: 410ppm
pH: 7.83 - 7.87
Alk dropped a lot, pH a little, Ca stayed the same. So I guess I'll go longer with the dosers off and see how much Ca moves. Then try to do the math on how much should really be dosed. This may take a while to get right!

 

[Ocelaris]

Dkh and ppm are not the same measurements, so that is about equal. 8 dkh is like 145 ppm, you can adjust the math, but alkalinity will always appear to drop more because they're different measurements and there is less alk to start with. Can you spread out the dosing more? I do it all day long with my Apex, half an hour apart.

Do you stir your sand bed? A turkey baster is a great tool to have for that.

 

[don_chuwish]

Thanks for the input!

Alk dropped from about 175ppm to 155ppm and Ca didn't budge, I'm not quite sure what to make of that. But it's only been one day.
I stir up the sand bed quite aggressively at water change time - vacuuming it a lot. That's when I started to notice the clumping.
Spreading the dosing out all day would be fine I suppose - originally I had been trying to even out the day/night pH swing by dosing at night. But looking at my pH chart I could probably get an even tighter range by spreading it out longer.
You can see where I didn't dose last night:

 

[Randy Holmes-Farley]

Thanks for the input!

Alk dropped from about 175ppm to 155ppm and Ca didn't budge, I'm not quite sure what to make of that. But it's only been one day.
I stir up the sand bed quite aggressively at water change time - vacuuming it a lot. That's when I started to notice the clumping.
Spreading the dosing out all day would be fine I suppose - originally I had been trying to even out the day/night pH swing by dosing at night. But looking at my pH chart I could probably get an even tighter range by spreading it out longer.
You can see where I didn't dose last night:

If that alkalinity drop (20 ppm calcium carbonate equivalents) is accurate, then calcium likely did drop by the expected amount of about 8-10 ppm, and the kit just couldn't distinguish it.

It is not unusual for sand to harden, especially when it is new. here's my standard comment on it:

Clumping of sand may be purely abiotic, but may also be driven by biological processes, and most often happens with new sand.
Reduced precipitation can be reached with lower pH, alkalinity and to a much smaller extent, calcium, and higher magnesium, organics, and phosphate.

Fresh CaCO3 surfaces can be most prone to more precipitation. To break the cycle, it can be useful to stop dosing for a few days, let alk fall and precipitation stop, then restart with a much lower dose.

 

[A4goulet]

This has happended to me recently where precipitation was causing my sand to clump. As recommended I stop dosing and allowed alk and ph to drop over a few days/week until my alk leveled out. Measured alk daily to establish actual alk consumption and dosed two part accordingly.

My question now is what to do with the hard sand bed? I started breaking some up but I belive it caused an ammonia spike. Now im left with clumpy sand in areas thats pretty unsightly. Do I continue breaking up the hard spots? Remove the clumps? Or will it all slowly break down?

 

[Randy Holmes-Farley]

This has happended to me recently where precipitation was causing my sand to clump. As recommended I stop dosing and allowed alk and ph to drop over a few days/week until my alk leveled out. Measured alk daily to establish actual alk consumption and dosed two part accordingly.

My question now is what to do with the hard sand bed? I started breaking some up but I belive it caused an ammonia spike. Now im left with clumpy sand in areas thats pretty unsightly. Do I continue breaking up the hard spots? Remove the clumps? Or will it all slowly break down?

Leaving it there is not generally an issue, but if it is unsightly, taking it out is also generally OK..

 

[don_chuwish]

If that alkalinity drop (20 ppm calcium carbonate equivalents) is accurate, then calcium likely did drop by the expected amount of about 8-10 ppm, and the kit just couldn't distinguish it.

It is not unusual for sand to harden, especially when it is new. here's my standard comment on it:

Clumping of sand may be purely abiotic, but may also be driven by biological processes, and most often happens with new sand.
Reduced precipitation can be reached with lower pH, alkalinity and to a much smaller extent, calcium, and higher magnesium, organics, and phosphate.

Fresh CaCO3 surfaces can be most prone to more precipitation. To break the cycle, it can be useful to stop dosing for a few days, let alk fall and precipitation stop, then restart with a much lower dose.

Thanks Randy! Yes it was that blurb in another thread somewhere that prompted me to stop dosing. I’ll re-evaluate on Sunday and see how I want to adjust dosing.
Also agreed - 10-20ppm is easy to miss with the titration. One or two drops either way each time you test.

 

[don_chuwish]

Today, after dosers off since Thursday:
Alk: 7.34dkh (131ppm)
Ca: 410ppm (unchanged)
pH: 7.7 - 7.8

Not really trusting that Ca number so the test vials are all getting a good vinegar bath right now. Will retest later today. But in terms of accuracy vs precision - it's the same 'well rinsed' test vial the past 3 tests.

Could Ca be re-entering the water as pH drops? Dissolving off where it had precipitated out previously?

 

[brandon429]

One thing we talk about in our sand rinse thread are the myriad benefits of starting a reef with absolutely blast rinsed new sand...tap water rinsed for half an hour or better, then salt rinsed before use, zero cloudability, no silt whatsoever and nothing to add flocculant for in the water. You can work it or gyre it however you want as the grain selection for strong currents was hand completed. Trick of the year

we are able to opt out of a diatoms invasion stage in new reefs with that prep...and cyano invasions. the high surface area silt truly does seem to correlate with biovavilable si or other means of making temporary opportunistic invaders bloom. The reason it's occurring is because ninety nine percent of reefers would never pre rinse a sandbed, they start with and keep the full range of substrate...non stratified mixes of fine powder all the way up to chipped clam shells. The bag says live for a reason, so people won't touch due to concern for the bacteria after a rinse. Taking time to start without the finest portions mixed in may have multiple benefits that only a few practitioners are seeing

I bet these high fraction silt inclusions are the cling hub for the little matrices that mortar a bed together. What if the practice of not pre rinsing, which is fueling thousands of tank invasions, is also causing the bed hardening phenomenon

wish we could chemically test what it would take to bind up a set of pre rinsed ocean direct, wonder if it takes higher levels of sustained dosers and pH boosts because only larger grains are left


has anyone ever reported a crushed coral sandbed that got bricked or is it just DSB types Randy that would be neat to know

 

[don_chuwish]

Thanks Bradon! This sand was well rinsed Tropic Eden Reefflakes and Miniflakes (about 2:1) - which start out very clean to begin with. I too hate the fine stuff.
Miniflakes - 2.0mm
Reefflakes - 3.0mm

It also gets vacuumed thoroughly every 4-6 weeks at WC time.

 

[don_chuwish]

Retested Ca with perfectly cleaned test vial and got:
420ppm - UP by 10ppm

So while the test isn't perfectly accurate it does seem to be fairly consistent.

I have no idea what to do with this information and restarting dosing. Should I dose ONLY Alk for a while?

 

[Randy Holmes-Farley]

Today, after dosers off since Thursday:
Alk: 7.34dkh (131ppm)
Ca: 410ppm (unchanged)
pH: 7.7 - 7.8

Not really trusting that Ca number so the test vials are all getting a good vinegar bath right now. Will retest later today. But in terms of accuracy vs precision - it's the same 'well rinsed' test vial the past 3 tests.

Could Ca be re-entering the water as pH drops? Dissolving off where it had precipitated out previously?

If the pH dropped well down into the sevens that can happen, but alk rises 2.8 dKH for each 18-20 ppm of calcium rise. The calcium cannot escape without the alk escaping.

 

[Randy Holmes-Farley]

Retested Ca with perfectly cleaned test vial and got:
420ppm - UP by 10ppm

So while the test isn't perfectly accurate it does seem to be fairly consistent.

I have no idea what to do with this information and restarting dosing. Should I dose ONLY Alk for a while?

I’d stick to dosing both parts of a two part unless calcium is already too high (500+ ppm).

 

[don_chuwish]

okeydoke, thanks!

 

[don_chuwish]

If the pH dropped well down into the sevens that can happen, but alk rises 2.8 dKH for each 18-20 ppm of calcium rise. The calcium cannot escape without the alk escaping.

I think I kinda knew that was the case - realized after posting that it was probably a silly idea. Thanks!
I'll be restarting dosing at half the previous amounts tonight.

 

[don_chuwish]

OK, one week of dosing HALF as much as before and the numbers are:

Alk: 8.46dkh (151ppm)
Ca: 410-420ppm
pH: 7.7 - 7.9

Alk is probably still on the way up, it's gone up every time I measure.

 

[Randy Holmes-Farley]

OK, one week of dosing HALF as much as before and the numbers are:

Alk: 8.46dkh (151ppm)
Ca: 410-420ppm
pH: 7.7 - 7.9

Alk is probably still on the way up, it's gone up every time I measure.

Those values seem good. [emoji3]

 

[don_chuwish]

Thanks, yes I'm especially pleased to go through less ESV product!

 

[ELChingonsReef]

If that alkalinity drop (20 ppm calcium carbonate equivalents) is accurate, then calcium likely did drop by the expected amount of about 8-10 ppm, and the kit just couldn't distinguish it.

It is not unusual for sand to harden, especially when it is new. here's my standard comment on it:

Clumping of sand may be purely abiotic, but may also be driven by biological processes, and most often happens with new sand.
Reduced precipitation can be reached with lower pH, alkalinity and to a much smaller extent, calcium, and higher magnesium, organics, and phosphate.

Fresh CaCO3 surfaces can be most prone to more precipitation. To break the cycle, it can be useful to stop dosing for a few days, let alk fall and precipitation stop, then restart with a much lower dose.

Hi randy. I've been having the same problem with my sand bed. It's a year old now. I do keep my PH high with a co2 scrubber. I keep alkalinity at 8.2ppm I herd soda ash turns sand to concrete. Is this true. I used BRS soda ash for alkalinity for a while. I stopped a couple months ago im using red sea foundation ABC . The sand is still clumpy. I'm wondering if I should find another 2part alkalinity solution.